diff --git a/overlay_buffer.c b/overlay_buffer.c
index 78f25218..cfb278b7 100644
--- a/overlay_buffer.c
+++ b/overlay_buffer.c
@@ -44,11 +44,11 @@ struct overlay_buffer *_ob_new(struct __sourceloc __whence)
 
 // index an existing static buffer.
 // and allow other callers to use the ob_ convenience methods for reading and writing up to size bytes.
-struct overlay_buffer *_ob_static(struct __sourceloc __whence, unsigned char *bytes, int size)
+struct overlay_buffer *_ob_static(struct __sourceloc __whence, unsigned char *bytes, size_t size)
 {
   struct overlay_buffer *ret = emalloc_zero(sizeof(struct overlay_buffer));
   if (config.debug.overlaybuffer)
-    DEBUGF("ob_static(bytes=%p, size=%d) return %p", bytes, size, ret);
+    DEBUGF("ob_static(bytes=%p, size=%zu) return %p", bytes, size, ret);
   if (ret == NULL)
     return NULL;
   ret->bytes = bytes;
@@ -61,18 +61,18 @@ struct overlay_buffer *_ob_static(struct __sourceloc __whence, unsigned char *by
 // create a new overlay buffer from an existing piece of another buffer.
 // Both buffers will point to the same memory region.
 // It is up to the caller to ensure this buffer is not used after the parent buffer is freed.
-struct overlay_buffer *_ob_slice(struct __sourceloc __whence, struct overlay_buffer *b, int offset, int length)
+struct overlay_buffer *_ob_slice(struct __sourceloc __whence, struct overlay_buffer *b, size_t offset, size_t length)
 {
-  if (offset+length > b->allocSize) {
+  if (offset + length > b->allocSize) {
     WHY("Buffer isn't long enough to slice");
     return NULL;
   }
   struct overlay_buffer *ret = emalloc_zero(sizeof(struct overlay_buffer));
   if (config.debug.overlaybuffer)
-    DEBUGF("ob_slice(b=%p, offset=%d, length=%d) return %p", b, offset, length, ret);
+    DEBUGF("ob_slice(b=%p, offset=%zu, length=%zu) return %p", b, offset, length, ret);
   if (ret == NULL)
       return NULL;
-  ret->bytes = b->bytes+offset;
+  ret->bytes = b->bytes + offset;
   ret->allocSize = length;
   ret->allocated = NULL;
   ob_unlimitsize(ret);
@@ -91,9 +91,11 @@ struct overlay_buffer *_ob_dup(struct __sourceloc __whence, struct overlay_buffe
   ret->checkpointLength = b->checkpointLength;
   if (b->bytes && b->allocSize){
     // duplicate any bytes that might be relevant
-    int byteCount = b->sizeLimit;
-    if (byteCount < b->position)
-      byteCount = b->position;
+    size_t byteCount = b->position;
+    if (b->sizeLimit != SIZE_MAX) {
+      assert(b->position <= b->sizeLimit);
+      byteCount = b->sizeLimit;
+    }
     if (byteCount > b->allocSize)
       byteCount = b->allocSize;
     if (byteCount)
@@ -117,7 +119,7 @@ int _ob_checkpoint(struct __sourceloc __whence, struct overlay_buffer *b)
   assert(b != NULL);
   b->checkpointLength = b->position;
   if (config.debug.overlaybuffer)
-    DEBUGF("ob_checkpoint(b=%p) checkpointLength=%d", b, b->checkpointLength);
+    DEBUGF("ob_checkpoint(b=%p) checkpointLength=%zu", b, b->checkpointLength);
   return 0;
 }
 
@@ -126,30 +128,29 @@ int _ob_rewind(struct __sourceloc __whence, struct overlay_buffer *b)
   assert(b != NULL);
   b->position = b->checkpointLength;
   if (config.debug.overlaybuffer)
-    DEBUGF("ob_rewind(b=%p) position=%d", b, b->position);
+    DEBUGF("ob_rewind(b=%p) position=%zu", b, b->position);
   return 0;
 }
 
-void _ob_limitsize(struct __sourceloc __whence, struct overlay_buffer *b, int bytes)
+void _ob_limitsize(struct __sourceloc __whence, struct overlay_buffer *b, size_t bytes)
 {
   assert(b != NULL);
-  assert(bytes >= 0);
-  assert(b->position >= 0);
+  assert(bytes != SIZE_MAX);
   assert(b->position <= bytes);
   assert(b->checkpointLength <= bytes);
   if (b->bytes && b->allocated == NULL)
     assert(bytes <= b->allocSize);
   b->sizeLimit = bytes;
   if (config.debug.overlaybuffer)
-    DEBUGF("ob_limitsize(b=%p, bytes=%d) sizeLimit=%d", b, bytes, b->sizeLimit);
+    DEBUGF("ob_limitsize(b=%p, bytes=%zu) sizeLimit=%zu", b, bytes, b->sizeLimit);
 }
 
 void _ob_unlimitsize(struct __sourceloc __whence, struct overlay_buffer *b)
 {
   assert(b != NULL);
-  b->sizeLimit = -1;
+  b->sizeLimit = SIZE_MAX;
   if (config.debug.overlaybuffer)
-    DEBUGF("ob_unlimitsize(b=%p) sizeLimit=%d", b, b->sizeLimit);
+    DEBUGF("ob_unlimitsize(b=%p) sizeLimit=%zu", b, b->sizeLimit);
 }
 
 void _ob_flip(struct __sourceloc __whence, struct overlay_buffer *b)
@@ -167,17 +168,15 @@ ssize_t _ob_makespace(struct __sourceloc __whence, struct overlay_buffer *b, siz
 {
   assert(b != NULL);
   if (config.debug.overlaybuffer)
-    DEBUGF("ob_makespace(b=%p, bytes=%zd) b->bytes=%p b->position=%d b->allocSize=%d",
+    DEBUGF("ob_makespace(b=%p, bytes=%zd) b->bytes=%p b->position=%zu b->allocSize=%zu",
 	   b, bytes, b->bytes, b->position, b->allocSize);
-  assert(b->position >= 0);
-  if (b->sizeLimit != -1)
-    assert(b->sizeLimit >= 0);
-  assert(b->allocSize >= 0);
+  assert(b->position <= b->sizeLimit);
+  assert(b->position <= b->allocSize);
   if (b->position)
     assert(b->bytes != NULL);
-  if (b->sizeLimit != -1 && b->position + bytes > b->sizeLimit) {
+  if (b->position + bytes > b->sizeLimit) {
     if (config.debug.packetformats)
-      DEBUGF("ob_makespace(): asked for space to %zu, beyond size limit of %u", b->position + bytes, b->sizeLimit);
+      DEBUGF("ob_makespace(): asked for space to %zu, beyond size limit of %zu", b->position + bytes, b->sizeLimit);
     return 0;
   }
   if (b->position + bytes <= b->allocSize)
@@ -185,10 +184,10 @@ ssize_t _ob_makespace(struct __sourceloc __whence, struct overlay_buffer *b, siz
   // Don't realloc a static buffer.
   if (b->bytes && b->allocated == NULL) {
     if (config.debug.packetformats)
-      DEBUGF("ob_makespace(): asked for space to %zu, beyond static buffer size of %u", b->position + bytes, b->allocSize);
+      DEBUGF("ob_makespace(): asked for space to %zu, beyond static buffer size of %zu", b->position + bytes, b->allocSize);
     return 0;
   }
-  int newSize=b->position+bytes;
+  size_t newSize = b->position + bytes;
   if (newSize<64) newSize=64;
   if (newSize&63) newSize+=64-(newSize&63);
   if (newSize>1024 && (newSize&1023))
@@ -196,7 +195,7 @@ ssize_t _ob_makespace(struct __sourceloc __whence, struct overlay_buffer *b, siz
   if (newSize>65536 && (newSize&65535))
     newSize+=65536-(newSize&65535);
   if (config.debug.overlaybuffer)
-    DEBUGF("realloc(b->bytes=%p,newSize=%d)", b->bytes,newSize);
+    DEBUGF("realloc(b->bytes=%p, newSize=%zu)", b->bytes, newSize);
   /* XXX OSX realloc() seems to be able to corrupt things if the heap is not happy when calling realloc(), making debugging memory corruption much harder.
     So will do a three-stage malloc,bcopy,free to see if we can tease bugs out that way. */
   /*
@@ -247,35 +246,35 @@ void _ob_append_byte(struct __sourceloc __whence, struct overlay_buffer *b, unsi
   if (ob_makespace(b, bytes)) {
     b->bytes[b->position] = byte;
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_byte(b=%p, byte=0x%02x) %p[%d]=%02x position=%d", b, byte, b->bytes, b->position, byte, b->position + bytes);
+      DEBUGF("ob_append_byte(b=%p, byte=0x%02x) %p[%d]=%02x position=%zu", b, byte, b->bytes, b->position, byte, b->position + bytes);
   } else {
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_byte(b=%p, byte=0x%02x) OVERRUN position=%d", b, byte, b->position + bytes);
+      DEBUGF("ob_append_byte(b=%p, byte=0x%02x) OVERRUN position=%zu", b, byte, b->position + bytes);
   }
   b->position += bytes;
 }
 
-unsigned char *_ob_append_space(struct __sourceloc __whence, struct overlay_buffer *b, int count)
+unsigned char *_ob_append_space(struct __sourceloc __whence, struct overlay_buffer *b, size_t count)
 {
   assert(count > 0);
   unsigned char *r = ob_makespace(b, count) ? &b->bytes[b->position] : NULL;
   b->position += count;
   if (config.debug.overlaybuffer)
-    DEBUGF("ob_append_space(b=%p, count=%d) position=%d return %p", b, count, b->position, r);
+    DEBUGF("ob_append_space(b=%p, count=%zu) position=%zu return %p", b, count, b->position, r);
   return r;
 }
 
-void _ob_append_bytes(struct __sourceloc __whence, struct overlay_buffer *b, const unsigned char *bytes, int count)
+void _ob_append_bytes(struct __sourceloc __whence, struct overlay_buffer *b, const unsigned char *bytes, size_t count)
 {
   assert(count > 0);
   unsigned char *r = ob_makespace(b, count) ? &b->bytes[b->position] : NULL;
   if (r) {
     bcopy(bytes, r, count);
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_bytes(b=%p, bytes=%p, count=%d) position=%d return %p", b, bytes, count, b->position + count, r);
+      DEBUGF("ob_append_bytes(b=%p, bytes=%p, count=%zu) position=%zu return %p", b, bytes, count, b->position + count, r);
   } else {
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_bytes(b=%p, bytes=%p, count=%d) OVERRUN position=%d return NULL", b, bytes, count, b->position + count);
+      DEBUGF("ob_append_bytes(b=%p, bytes=%p, count=%zu) OVERRUN position=%zu return NULL", b, bytes, count, b->position + count);
   }
   if (config.debug.overlaybuffer)
     dump("ob_append_bytes", bytes, count);
@@ -294,10 +293,10 @@ void _ob_append_ui16(struct __sourceloc __whence, struct overlay_buffer *b, uint
     b->bytes[b->position] = (v >> 8) & 0xFF;
     b->bytes[b->position+1] = v & 0xFF;
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_ui16(b=%p, v=%u) %p[%d]=%s position=%d", b, v, b->bytes, b->position, alloca_tohex(&b->bytes[b->position], bytes), b->position + bytes);
+      DEBUGF("ob_append_ui16(b=%p, v=%u) %p[%d]=%s position=%zu", b, v, b->bytes, b->position, alloca_tohex(&b->bytes[b->position], bytes), b->position + bytes);
   } else {
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_ui16(b=%p, v=%u) OVERRUN position=%d", b, v, b->position + bytes);
+      DEBUGF("ob_append_ui16(b=%p, v=%u) OVERRUN position=%zu", b, v, b->position + bytes);
   }
   b->position += bytes;
 }
@@ -311,11 +310,11 @@ void _ob_append_ui32(struct __sourceloc __whence, struct overlay_buffer *b, uint
     b->bytes[b->position+2] = (v >> 8) & 0xFF;
     b->bytes[b->position+3] = v & 0xFF;
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_ui32(b=%p, v=%"PRIu32") %p[%d]=%s position=%d",
+      DEBUGF("ob_append_ui32(b=%p, v=%"PRIu32") %p[%d]=%s position=%zu",
 	  b, v, b->bytes, b->position, alloca_tohex(&b->bytes[b->position], bytes), b->position + bytes);
   } else {
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_ui32(b=%p, v=%"PRIu32") OVERRUN position=%d", b, v, b->position + bytes);
+      DEBUGF("ob_append_ui32(b=%p, v=%"PRIu32") OVERRUN position=%zu", b, v, b->position + bytes);
   }
   b->position += bytes;
 }
@@ -333,11 +332,11 @@ void _ob_append_ui64(struct __sourceloc __whence, struct overlay_buffer *b, uint
     b->bytes[b->position+6] = (v >> 8) & 0xFF;
     b->bytes[b->position+7] = v & 0xFF;
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_ui64(b=%p, v=%"PRIu64") %p[%d]=%s position=%d",
+      DEBUGF("ob_append_ui64(b=%p, v=%"PRIu64") %p[%d]=%s position=%zu",
 	  b, v, b->bytes, b->position, alloca_tohex(&b->bytes[b->position], bytes), b->position + bytes);
   } else {
     if (config.debug.overlaybuffer)
-      DEBUGF("ob_append_ui64(b=%p, v=%"PRIu64") OVERRUN position=%d", b, v, b->position + bytes);
+      DEBUGF("ob_append_ui64(b=%p, v=%"PRIu64") OVERRUN position=%zu", b, v, b->position + bytes);
   }
   b->position += bytes;
 }
@@ -407,19 +406,19 @@ void _ob_append_rfs(struct __sourceloc __whence, struct overlay_buffer *b, int l
 
 
 // make sure a range of bytes is valid for reading
-int test_offset(struct overlay_buffer *b,int start,int length)
+static int test_offset(struct overlay_buffer *b, size_t length)
 {
-  if (!b) return -1;
-  if (start<0) return -1;
-  if (b->sizeLimit>=0 && start+length>b->sizeLimit) return -1;
-  if (start+length>b->allocSize) return -1;
+  if (b->position + length > b->sizeLimit)
+    return -1;
+  if (b->position + length > b->allocSize)
+    return -1;
   return 0;
 }
 
 // next byte without advancing
 int ob_peek(struct overlay_buffer *b)
 {
-  if (test_offset(b, b->position, 1))
+  if (test_offset(b, 1))
     return -1;
   return b->bytes[b->position];
 }
@@ -429,19 +428,19 @@ void ob_skip(struct overlay_buffer *b, unsigned n)
   b->position += n;
 }
 
-int ob_get_bytes(struct overlay_buffer *b, unsigned char *buff, int len){
-  if (test_offset(b, b->position, len))
+int ob_get_bytes(struct overlay_buffer *b, unsigned char *buff, size_t len)
+{
+  if (test_offset(b, len))
     return -1;
-  
   bcopy(b->bytes + b->position, buff, len);
   b->position+=len;
   return 0;
 }
 
-unsigned char * ob_get_bytes_ptr(struct overlay_buffer *b, int len){
-  if (test_offset(b, b->position, len))
+unsigned char * ob_get_bytes_ptr(struct overlay_buffer *b, size_t len)
+{
+  if (test_offset(b, len))
     return NULL;
-  
   unsigned char *ret = b->bytes + b->position;
   b->position+=len;
   return ret;
@@ -449,9 +448,8 @@ unsigned char * ob_get_bytes_ptr(struct overlay_buffer *b, int len){
 
 uint32_t ob_get_ui32(struct overlay_buffer *b)
 {
-  if (test_offset(b, b->position, 4))
+  if (test_offset(b, 4))
     return 0xFFFFFFFF; // ... unsigned
-
   uint32_t ret = b->bytes[b->position] << 24
 	| b->bytes[b->position +1] << 16
 	| b->bytes[b->position +2] << 8
@@ -462,9 +460,8 @@ uint32_t ob_get_ui32(struct overlay_buffer *b)
 
 uint64_t ob_get_ui64(struct overlay_buffer *b)
 {
-  if (test_offset(b, b->position, 8))
+  if (test_offset(b, 8))
     return 0xFFFFFFFF; // ... unsigned
-
   uint64_t ret = (uint64_t)b->bytes[b->position] << 56
 	| (uint64_t)b->bytes[b->position +1] << 48
 	| (uint64_t)b->bytes[b->position +2] << 40
@@ -479,9 +476,8 @@ uint64_t ob_get_ui64(struct overlay_buffer *b)
 
 uint16_t ob_get_ui16(struct overlay_buffer *b)
 {
-  if (test_offset(b, b->position, 2))
+  if (test_offset(b, 2))
     return 0xFFFF; // ... unsigned
-  
   uint16_t ret = b->bytes[b->position] << 8
 	| b->bytes[b->position +1];
   b->position+=2;
@@ -520,18 +516,16 @@ uint64_t ob_get_packed_ui64(struct overlay_buffer *b)
 
 int ob_get(struct overlay_buffer *b)
 {
-  if (test_offset(b, b->position, 1))
+  if (test_offset(b, 1))
     return -1;
   return b->bytes[b->position++];
 }
 
-void _ob_set_ui16(struct __sourceloc __whence, struct overlay_buffer *b, int offset, uint16_t v)
+void _ob_set_ui16(struct __sourceloc __whence, struct overlay_buffer *b, size_t offset, uint16_t v)
 {
   const int bytes = 2;
   assert(b != NULL);
-  assert(offset >= 0);
-  if (b->sizeLimit != -1)
-    assert(offset + bytes <= b->sizeLimit);
+  assert(offset + bytes <= b->sizeLimit);
   assert(offset + bytes <= b->allocSize);
   b->bytes[offset] = (v >> 8) & 0xFF;
   b->bytes[offset+1] = v & 0xFF;
@@ -539,13 +533,11 @@ void _ob_set_ui16(struct __sourceloc __whence, struct overlay_buffer *b, int off
     DEBUGF("ob_set_ui16(b=%p, offset=%d, v=%u) %p[%d]=%s", b, offset, v, b->bytes, offset, alloca_tohex(&b->bytes[offset], bytes));
 }
 
-void _ob_set(struct __sourceloc __whence, struct overlay_buffer *b, int offset, unsigned char byte)
+void _ob_set(struct __sourceloc __whence, struct overlay_buffer *b, size_t offset, unsigned char byte)
 {
   const int bytes = 1;
   assert(b != NULL);
-  assert(offset >= 0);
-  if (b->sizeLimit != -1)
-    assert(offset + bytes <= b->sizeLimit);
+  assert(offset + bytes <= b->sizeLimit);
   assert(offset + bytes <= b->allocSize);
   b->bytes[offset] = byte;
   if (config.debug.overlaybuffer)
@@ -558,28 +550,26 @@ void _ob_patch_rfs(struct __sourceloc __whence, struct overlay_buffer *b)
 }
 
 
-int ob_position(struct overlay_buffer *b)
+size_t ob_position(struct overlay_buffer *b)
 {
   return b->position;
 }
 
-int ob_limit(struct overlay_buffer *b)
+size_t ob_limit(struct overlay_buffer *b)
 {
   return b->sizeLimit;
 }
 
-int ob_remaining(struct overlay_buffer *b)
+size_t ob_remaining(struct overlay_buffer *b)
 {
-  assert(b->sizeLimit != -1);
-  return b->sizeLimit - b->position;
+  assert(b->sizeLimit != SIZE_MAX);
+  assert(b->position <= b->sizeLimit);
+  return (size_t)(b->sizeLimit - b->position);
 }
 
 int _ob_overrun(struct __sourceloc __whence, struct overlay_buffer *b)
 {
-  assert(b->allocSize >= 0);
-  if (b->sizeLimit != -1)
-    assert(b->sizeLimit >= 0);
-  int ret = b->position > (b->sizeLimit != -1 && b->sizeLimit < b->allocSize ? b->sizeLimit : b->allocSize);
+  int ret = b->position > (b->sizeLimit != SIZE_MAX && b->sizeLimit < b->allocSize ? b->sizeLimit : b->allocSize);
   if (config.debug.overlaybuffer)
     DEBUGF("ob_overrun(b=%p) return %d", b, ret);
   return ret;
@@ -599,8 +589,13 @@ int asprintable(int c)
 
 int ob_dump(struct overlay_buffer *b, char *desc)
 {
-  DEBUGF("overlay_buffer '%s' at %p (%p) : position=%d, size=%d", desc, b, b->bytes, b->position, b->sizeLimit);
-  if (b->bytes && (b->position || b->sizeLimit))
-    dump(desc, b->bytes, b->position?b->position:b->sizeLimit);
+  DEBUGF("overlay_buffer '%s' at %p (%p) : position=%zu, size=%zu", desc, b, b->bytes, b->position, b->sizeLimit);
+  if (b->bytes) {
+    if (b->sizeLimit != SIZE_MAX && b->sizeLimit > 0) {
+      assert(b->position <= b->sizeLimit);
+      dump(desc, b->bytes, b->sizeLimit);
+    } else if (b->position > 0)
+      dump(desc, b->bytes, b->position);
+  }
   return 0;
 }
diff --git a/overlay_buffer.h b/overlay_buffer.h
index 7aa3c5e4..a9cb4df9 100644
--- a/overlay_buffer.h
+++ b/overlay_buffer.h
@@ -24,43 +24,43 @@ struct overlay_buffer {
   unsigned char *bytes;
   
   // remembered position for rewinding
-  int checkpointLength;
+  size_t checkpointLength;
   
   // position of data read / written
-  int position;
+  size_t position;
   
   // maximum allowed bytes for reading / writing
-  int sizeLimit;
+  size_t sizeLimit;
   
   // size of buffer
-  int allocSize;
+  size_t allocSize;
   
   // is this an allocated buffer? can it be resized? Should it be freed?
   unsigned char * allocated;
   
   // length position for later patching
-  int var_length_offset;
+  size_t var_length_offset;
 };
 
 struct overlay_buffer *_ob_new(struct __sourceloc __whence);
-struct overlay_buffer *_ob_static(struct __sourceloc __whence, unsigned char *bytes, int size);
-struct overlay_buffer *_ob_slice(struct __sourceloc __whence, struct overlay_buffer *b, int offset, int length);
+struct overlay_buffer *_ob_static(struct __sourceloc __whence, unsigned char *bytes, size_t size);
+struct overlay_buffer *_ob_slice(struct __sourceloc __whence, struct overlay_buffer *b, size_t offset, size_t length);
 struct overlay_buffer *_ob_dup(struct __sourceloc __whence, struct overlay_buffer *b);
 void _ob_free(struct __sourceloc __whence, struct overlay_buffer *b);
 int _ob_checkpoint(struct __sourceloc __whence, struct overlay_buffer *b);
 int _ob_rewind(struct __sourceloc __whence, struct overlay_buffer *b);
-void _ob_limitsize(struct __sourceloc __whence, struct overlay_buffer *b,int bytes);
+void _ob_limitsize(struct __sourceloc __whence, struct overlay_buffer *b, size_t bytes);
 void _ob_flip(struct __sourceloc __whence, struct overlay_buffer *b);
 void _ob_unlimitsize(struct __sourceloc __whence, struct overlay_buffer *b);
 ssize_t _ob_makespace(struct __sourceloc whence, struct overlay_buffer *b, size_t bytes);
-void _ob_set(struct __sourceloc __whence, struct overlay_buffer *b, int ofs, unsigned char byte);
-void _ob_set_ui16(struct __sourceloc __whence, struct overlay_buffer *b, int offset, uint16_t v);
+void _ob_set(struct __sourceloc __whence, struct overlay_buffer *b, size_t ofs, unsigned char byte);
+void _ob_set_ui16(struct __sourceloc __whence, struct overlay_buffer *b, size_t offset, uint16_t v);
 void _ob_patch_rfs(struct __sourceloc __whence, struct overlay_buffer *b);
 
 void _ob_append_byte(struct __sourceloc whence, struct overlay_buffer *b,unsigned char byte);
-void _ob_append_bytes(struct __sourceloc whence, struct overlay_buffer *b,const unsigned char *bytes,int count);
+void _ob_append_bytes(struct __sourceloc whence, struct overlay_buffer *b,const unsigned char *bytes, size_t count);
 void _ob_append_buffer(struct __sourceloc whence, struct overlay_buffer *b,struct overlay_buffer *s);
-unsigned char *_ob_append_space(struct __sourceloc whence, struct overlay_buffer *b,int count);
+unsigned char *_ob_append_space(struct __sourceloc whence, struct overlay_buffer *b, size_t count);
 void _ob_append_ui16(struct __sourceloc whence, struct overlay_buffer *b, uint16_t v);
 void _ob_append_ui32(struct __sourceloc whence, struct overlay_buffer *b, uint32_t v);
 void _ob_append_ui64(struct __sourceloc whence, struct overlay_buffer *b, uint64_t v);
@@ -99,8 +99,8 @@ int ob_peek(struct overlay_buffer *b);
 void ob_skip(struct overlay_buffer *b, unsigned n);
 // get one byte from the current position, -ve number indicates failure
 int ob_get(struct overlay_buffer *b);
-int ob_get_bytes(struct overlay_buffer *b, unsigned char *buff, int len);
-unsigned char * ob_get_bytes_ptr(struct overlay_buffer *b, int len);
+int ob_get_bytes(struct overlay_buffer *b, unsigned char *buff, size_t len);
+unsigned char * ob_get_bytes_ptr(struct overlay_buffer *b, size_t len);
 uint64_t ob_get_ui64(struct overlay_buffer *b);
 uint32_t ob_get_ui32(struct overlay_buffer *b);
 uint16_t ob_get_ui16(struct overlay_buffer *b);
@@ -110,9 +110,9 @@ uint32_t ob_get_packed_ui32(struct overlay_buffer *b);
 uint64_t ob_get_packed_ui64(struct overlay_buffer *b);
 
 // information routines
-int ob_position(struct overlay_buffer *b);
-int ob_limit(struct overlay_buffer *b);
-int ob_remaining(struct overlay_buffer *b);
+size_t ob_position(struct overlay_buffer *b);
+size_t ob_limit(struct overlay_buffer *b);
+size_t ob_remaining(struct overlay_buffer *b);
 int _ob_overrun(struct __sourceloc, struct overlay_buffer *b);
 unsigned char* ob_ptr(struct overlay_buffer *b);
 
diff --git a/overlay_interface.c b/overlay_interface.c
index 44239bab..5a6c821d 100644
--- a/overlay_interface.c
+++ b/overlay_interface.c
@@ -810,13 +810,13 @@ int overlay_broadcast_ensemble(struct network_destination *destination, struct o
 {
   assert(destination && destination->interface);
   const unsigned char *bytes = ob_ptr(buffer);
-  int len = ob_position(buffer);
+  size_t len = ob_position(buffer);
   
   struct overlay_interface *interface = destination->interface;
   destination->last_tx = gettime_ms();
   
   if (config.debug.packettx){
-    DEBUGF("Sending this packet via interface %s (len=%d)",interface->name,len);
+    DEBUGF("Sending this packet via interface %s (len=%zu)",interface->name, len);
     DEBUG_packet_visualise(NULL, bytes, len);
   }
 
@@ -826,7 +826,7 @@ int overlay_broadcast_ensemble(struct network_destination *destination, struct o
   }
 
   if (interface->debug)
-    DEBUGF("Sending on %s, len %d: %s", interface->name, len, alloca_tohex(bytes, len>64?64:len));
+    DEBUGF("Sending on %s, len %zu: %s", interface->name, len, alloca_tohex(bytes, len>64?64:len));
 
   interface->tx_count++;
   
@@ -842,11 +842,11 @@ int overlay_broadcast_ensemble(struct network_destination *destination, struct o
 	.pid = getpid(),
       };
       
-      if (len > sizeof(packet.payload)){
+      if (len > sizeof packet.payload) {
 	WARN("Truncating long packet to fit within MTU byte limit for dummy interface");
-	len = sizeof(packet.payload);
+	len = sizeof packet.payload;
       }
-      packet.payload_length=len;
+      packet.payload_length = len;
       bcopy(bytes, packet.payload, len);
       ob_free(buffer);
       /* This lseek() is unneccessary because the dummy file is opened in O_APPEND mode.  It's
@@ -886,22 +886,22 @@ int overlay_broadcast_ensemble(struct network_destination *destination, struct o
     case SOCK_DGRAM:
     {
       if (config.debug.overlayinterfaces) 
-	DEBUGF("Sending %zu byte overlay frame on %s to %s", (size_t)len, interface->name, inet_ntoa(destination->address.sin_addr));
+	DEBUGF("Sending %zu byte overlay frame on %s to %s", len, interface->name, inet_ntoa(destination->address.sin_addr));
       ssize_t sent = sendto(interface->alarm.poll.fd, 
 		bytes, (size_t)len, 0, 
 		(struct sockaddr *)&destination->address, sizeof(destination->address));
       ob_free(buffer);
-      if (sent == -1 || (size_t)sent != (size_t)len) {
+      if (sent == -1 || (size_t)sent != len) {
 	if (sent == -1)
 	  WHYF_perror("sendto(fd=%d,len=%zu,addr=%s) on interface %s",
 	      interface->alarm.poll.fd,
-	      (size_t)len,
+	      len,
 	      alloca_sockaddr((struct sockaddr *)&destination->address, sizeof destination->address),
 	      interface->name
 	    );
 	else
 	  WHYF("sendto() sent %zu bytes of overlay frame (%zu) to interface %s (socket=%d)",
-	      (size_t)sent, (size_t)len, interface->name, interface->alarm.poll.fd);
+	      (size_t)sent, len, interface->name, interface->alarm.poll.fd);
 	// close the interface if we had any error while sending broadcast packets,
 	// unicast packets should not bring the interface down
 	if (destination == interface->destination)
diff --git a/overlay_mdp.c b/overlay_mdp.c
index 0b8c1538..613b0b35 100644
--- a/overlay_mdp.c
+++ b/overlay_mdp.c
@@ -766,7 +766,7 @@ static int overlay_send_frame(
   
   if (ob_overrun(plaintext)) {
     if (config.debug.mdprequests) 
-      DEBUGF("Frame overrun: position=%d allocSize=%d sizeLimit=%d",
+      DEBUGF("Frame overrun: position=%zu allocSize=%zu sizeLimit=%zu",
 	  plaintext->position, plaintext->allocSize, plaintext->sizeLimit);
     op_free(frame);
     ob_free(plaintext);
diff --git a/overlay_olsr.c b/overlay_olsr.c
index 57ed7911..aa4c4677 100644
--- a/overlay_olsr.c
+++ b/overlay_olsr.c
@@ -196,7 +196,7 @@ static void parse_frame(struct overlay_buffer *buff){
   frame.modifiers=ob_get(buff);
   
   if (config.debug.overlayinterfaces) 
-    DEBUGF("Received %d byte payload via olsr", buff->sizeLimit - buff->position);
+    DEBUGF("Received %zu byte payload via olsr", buff->sizeLimit - buff->position);
   
   // the remaining bytes are an mdp payload, process it
   frame.payload = buff;
@@ -297,7 +297,7 @@ int olsr_send(struct overlay_frame *frame){
   ob_append_byte(b, frame->modifiers);
   
   if (config.debug.overlayinterfaces) 
-    DEBUGF("Sending %d byte payload via olsr", frame->payload->sizeLimit);
+    DEBUGF("Sending %zu byte payload via olsr", frame->payload->sizeLimit);
   
   // send the packet
   int ret = send_packet(b->bytes, b->position, frame->payload->bytes, frame->payload->sizeLimit);
diff --git a/overlay_packetformats.c b/overlay_packetformats.c
index ffd18f86..1412fb44 100644
--- a/overlay_packetformats.c
+++ b/overlay_packetformats.c
@@ -425,7 +425,7 @@ int packetOkOverlay(struct overlay_interface *interface,unsigned char *packet, s
     }
     
     // TODO allow for single byte length?
-    unsigned int payload_len;
+    size_t payload_len;
     
     switch (context.encapsulation){
       case ENCAP_SINGLE:
@@ -459,7 +459,7 @@ int packetOkOverlay(struct overlay_interface *interface,unsigned char *packet, s
     
     if (header_valid!=0){
 
-      f.payload = ob_slice(b, b->position, payload_len);
+      f.payload = ob_slice(b, ob_position(b), payload_len);
       if (!f.payload){
 	// out of memory?
 	WHY("Unable to slice payload");
diff --git a/overlay_payload.c b/overlay_payload.c
index 05f43215..f7059d4c 100644
--- a/overlay_payload.c
+++ b/overlay_payload.c
@@ -94,7 +94,7 @@ int overlay_frame_append_payload(struct decode_context *context, int encapsulati
 	   alloca_tohex_sid_t(p->destination->sid),p->type,
 	   "append_payload stuffing into packet");
     if (p->payload)
-      dump("payload contents", &p->payload->bytes[0],p->payload->position);
+      dump("payload contents", &p->payload->bytes[0], ob_position(p->payload));
   }
   
   struct broadcast *broadcast=NULL;
diff --git a/overlay_queue.c b/overlay_queue.c
index 011a0504..88f73817 100644
--- a/overlay_queue.c
+++ b/overlay_queue.c
@@ -335,7 +335,7 @@ overlay_stuff_packet(struct outgoing_packet *packet, overlay_txqueue *queue, tim
   while(frame){
     if (frame->enqueued_at + queue->latencyTarget < now){
       if (config.debug.overlayframes)
-	DEBUGF("Dropping frame type %x (length %d) for %s due to expiry timeout", 
+	DEBUGF("Dropping frame type %x (length %zu) for %s due to expiry timeout", 
 	       frame->type, frame->payload->checkpointLength,
 	       frame->destination?alloca_tohex_sid_t(frame->destination->sid):"All");
       frame = overlay_queue_remove(queue, frame);
diff --git a/rhizome_packetformats.c b/rhizome_packetformats.c
index 5eec9688..8ed9899d 100644
--- a/rhizome_packetformats.c
+++ b/rhizome_packetformats.c
@@ -168,12 +168,12 @@ static int append_bars(struct overlay_buffer *e, sqlite_retry_state *retry, cons
 	DEBUG("Found a BAR that is the wrong size - ignoring");
       continue;
     }
-    if (ob_remaining(e) < blob_bytes) {
+    if (ob_remaining(e) < RHIZOME_BAR_BYTES) {
       // out of room
       count--;
       break;
     }
-    ob_append_bytes(e, (unsigned char *)data, blob_bytes);
+    ob_append_bytes(e, (unsigned char *)data, RHIZOME_BAR_BYTES);
     *last_rowid=rowid;
   }
   if (statement)
diff --git a/route_link.c b/route_link.c
index a8d612da..8761209b 100644
--- a/route_link.c
+++ b/route_link.c
@@ -488,7 +488,7 @@ static int append_link_state(struct overlay_buffer *payload, char flags,
     flags|=FLAG_HAS_ACK;
   if (drop_rate!=-1)
     flags|=FLAG_HAS_DROP_RATE;
-  int length_pos = ob_position(payload);
+  size_t length_pos = ob_position(payload);
   ob_append_byte(payload, 0);
   ob_append_byte(payload, flags);
   overlay_address_append(NULL, payload, receiver);
@@ -507,7 +507,7 @@ static int append_link_state(struct overlay_buffer *payload, char flags,
   if (ob_overrun(payload))
     return -1;
   // patch the record length
-  int end_pos = ob_position(payload);
+  size_t end_pos = ob_position(payload);
   ob_set(payload, length_pos, end_pos - length_pos);
   ob_checkpoint(payload);
   return 0;
@@ -898,7 +898,7 @@ static void link_send(struct sched_ent *alarm)
     ob_limitsize(frame->payload, 400);
     overlay_mdp_encode_ports(frame->payload, MDP_PORT_LINKSTATE, MDP_PORT_LINKSTATE);
     ob_checkpoint(frame->payload);
-    int pos = ob_position(frame->payload);
+    size_t pos = ob_position(frame->payload);
     enum_subscribers(NULL, append_link, frame->payload);
     ob_rewind(frame->payload);
     if (ob_position(frame->payload) == pos)
@@ -1243,7 +1243,7 @@ int link_receive(struct overlay_frame *frame, overlay_mdp_frame *mdp)
 
     struct subscriber *receiver=NULL, *transmitter=NULL;
     struct overlay_interface *interface = NULL;
-    int start_pos = ob_position(payload);
+    size_t start_pos = ob_position(payload);
     int length = ob_get(payload);
     if (length <=0)
       break;