diff --git a/commandline.c b/commandline.c
index ba118706..ae024d19 100644
--- a/commandline.c
+++ b/commandline.c
@@ -1051,7 +1051,7 @@ int app_mdp_ping(const struct cli_parsed *parsed, struct cli_context *context)
       uint8_t recv_payload[12];
       ssize_t len = mdp_recv(mdp_sockfd, &mdp_recv_header, recv_payload, sizeof(recv_payload));
       
-      if (len<0){
+      if (len == -1){
 	WHY_perror("mdp_recv");
 	break;
       }
@@ -1069,7 +1069,7 @@ int app_mdp_ping(const struct cli_parsed *parsed, struct cli_context *context)
 	continue;
       }
       
-      if (len<sizeof(recv_payload)){
+      if ((size_t)len < sizeof(recv_payload)){
 	DEBUGF("Ignoring ping response as it is too short");
 	continue;
       }
diff --git a/http_server.c b/http_server.c
index 1a2193a2..adaa6cae 100644
--- a/http_server.c
+++ b/http_server.c
@@ -1593,7 +1593,7 @@ static void http_request_send_response(struct http_request *r)
     if (r->phase != PAUSE)
       http_request_set_idle_timeout(r);
     // If we wrote less than we tried, then go back to polling, otherwise keep generating content.
-    if (written < (size_t) unsent)
+    if ((size_t) written < (size_t) unsent)
       return;
   }
   if (r->debug_flag && *r->debug_flag)
diff --git a/mdp_client.c b/mdp_client.c
index 2cb7e0e1..bc02fb20 100644
--- a/mdp_client.c
+++ b/mdp_client.c
@@ -119,8 +119,10 @@ ssize_t mdp_recv(int socket, struct mdp_header *header, uint8_t *payload, ssize_
   };
   
   ssize_t len = recvmsg(socket, &hdr, 0);
-  if (len<sizeof(struct mdp_header))
-    return WHYF("Received message is too short (%d)", (int)len);
+  if (len == -1)
+    return WHYF_perror("recvmsg(%d,%p,0)", socket, &hdr);
+  if ((size_t)len < sizeof(struct mdp_header))
+    return WHYF("Received message is too short (%zu)", (size_t)len);
   addr.addrlen=hdr.msg_namelen;
   // double check that the incoming address matches the servald daemon
   if (cmp_sockaddr(&addr, &mdp_addr) != 0
diff --git a/net.c b/net.c
index 8a3b7dfa..c1c6f5a6 100644
--- a/net.c
+++ b/net.c
@@ -81,7 +81,7 @@ ssize_t _write_all(int fd, const void *buf, size_t len, struct __sourceloc __whe
   if (written == -1)
     return WHYF_perror("write_all: write(%d,%p %s,%zu)",
 	fd, buf, alloca_toprint(30, buf, len), len);
-  if (written != len)
+  if ((size_t)written != len)
     return WHYF_perror("write_all: write(%d,%p %s,%zu) returned %zd",
 	fd, buf, alloca_toprint(30, buf, len), len, (size_t)written);
   return written;
@@ -96,7 +96,7 @@ ssize_t _writev_all(int fd, const struct iovec *iov, int iovcnt, struct __source
   ssize_t written = writev(fd, iov, iovcnt);
   if (written == -1)
     return WHYF_perror("writev_all: writev(%d,%s len=%zu)", fd, alloca_iovec(iov, iovcnt), len);
-  if (written != len)
+  if ((size_t)written != len)
     return WHYF_perror("writev_all: writev(%d,%s len=%zu) returned %zd", fd, alloca_iovec(iov, iovcnt), len, (size_t)written);
   return written;
 }
@@ -123,9 +123,9 @@ ssize_t _write_nonblock(int fd, const void *buf, size_t len, struct __sourceloc
 ssize_t _write_all_nonblock(int fd, const void *buf, size_t len, struct __sourceloc __whence)
 {
   ssize_t written = _write_nonblock(fd, buf, len, __whence);
-  if (written != -1 && written != len)
-    return WHYF("write_all_nonblock: write(%d,%p %s,%lu) returned %ld",
-	fd, buf, alloca_toprint(30, buf, len), (unsigned long)len, (long)written);
+  if (written != -1 && (size_t)written != len)
+    return WHYF("write_all_nonblock: write(%d,%p %s,%zu) returned %zd",
+	fd, buf, alloca_toprint(30, buf, len), len, (size_t)written);
   return written;
 }
 
diff --git a/os.c b/os.c
index 35d2e3de..8a1863e7 100644
--- a/os.c
+++ b/os.c
@@ -156,9 +156,9 @@ ssize_t read_symlink(const char *path, char *buf, size_t len)
   }
   ssize_t nr = readlink(path, buf, len);
   if (nr == -1)
-    return WHYF_perror("readlink(%s)", path);
-  if (nr >= len)
-    return WHYF("buffer overrun from readlink(%s, len=%lu)", path, (unsigned long) len);
+    return WHYF_perror("readlink(%s,%p,%zu)", path, buf, len);
+  if ((size_t)nr >= len)
+    return WHYF("buffer overrun from readlink(%s, len=%zu)", path, len);
   buf[nr] = '\0';
   return nr;
 }
diff --git a/overlay_mdp.c b/overlay_mdp.c
index 613b0b35..bb5726fe 100644
--- a/overlay_mdp.c
+++ b/overlay_mdp.c
@@ -1473,11 +1473,11 @@ static void mdp_poll2(struct sched_ent *alarm)
     struct iovec iov[]={
       {
 	.iov_base = (void *)&header,
-	.iov_len = sizeof(struct mdp_header)
+	.iov_len = sizeof header
       },
       {
 	.iov_base = (void *)payload,
-	.iov_len = sizeof(payload)
+	.iov_len = sizeof payload
       }
     };
     
@@ -1489,17 +1489,17 @@ static void mdp_poll2(struct sched_ent *alarm)
     };
     
     ssize_t len = recvmsg(alarm->poll.fd, &hdr, 0);
-    if (len<0){
-      WHY_perror("recvmsg");
+    if (len == -1){
+      WHYF_perror("recvmsg(%d,%p,0)", alarm->poll.fd, &hdr);
       return;
     }
-    if (len<sizeof(struct mdp_header)){
-      WHYF("Expected length %d, got %d from %s", (int)sizeof(struct mdp_header), (int)len, alloca_socket_address(&client));
+    if ((size_t)len < sizeof header) {
+      WHYF("Expected length %zu, got %zu from %s", sizeof header, len, alloca_socket_address(&client));
       return;
     }
     
     client.addrlen = hdr.msg_namelen;
-    size_t payload_len = len - sizeof(header);
+    size_t payload_len = (size_t)(len - sizeof header);
     mdp_process_packet(&client, &header, payload, payload_len);
   }
 }
@@ -1521,7 +1521,7 @@ static void overlay_mdp_poll(struct sched_ent *alarm)
 	    &client, alloca_socket_address(&client)
 	  );
 
-    if (len > 0) {
+    if ((size_t)len > 0) {
       if (client.addrlen <= sizeof(sa_family_t))
 	WHYF("got client.addrlen=%d too short -- ignoring frame len=%zu", (int)client.addrlen, (size_t)len);
       else {
diff --git a/rhizome.c b/rhizome.c
index 6955ad11..948d608d 100644
--- a/rhizome.c
+++ b/rhizome.c
@@ -144,10 +144,8 @@ int rhizome_bundle_import_files(rhizome_manifest *m, const char *manifest_path,
     }
     
     if (ret==0){
-      ret = fread(buffer, 1, buffer_len, f);
-      if (ret==buffer_len)
-	ret=0;
-      else
+      ssize_t nread = fread(buffer, 1, buffer_len, f);
+      if ((size_t)nread != buffer_len)
 	ret=WHY_perror("Unable to read manifest contents");
     }
     
diff --git a/rhizome_store.c b/rhizome_store.c
index c6ae9e39..96350f01 100644
--- a/rhizome_store.c
+++ b/rhizome_store.c
@@ -221,17 +221,17 @@ static int write_data(struct rhizome_write *write_state, uint64_t file_offset, u
     WARNF("Writing file data out of order! [%"PRId64",%"PRId64"]", file_offset, write_state->written_offset);
     
   if (write_state->blob_fd != -1) {
-    int ofs=0;
+    size_t ofs = 0;
     // keep trying until all of the data is written.
     if (lseek64(write_state->blob_fd, (off64_t) file_offset, SEEK_SET) == -1)
       return WHYF_perror("lseek64(%d,%"PRIu64",SEEK_SET)", write_state->blob_fd, file_offset);
-    while(ofs < data_size){
-      int r=write(write_state->blob_fd, buffer + ofs, data_size - ofs);
-      if (r<0)
+    while (ofs < data_size){
+      ssize_t r = write(write_state->blob_fd, buffer + ofs, (size_t)(data_size - ofs));
+      if (r == -1)
 	return WHY_perror("write");
       if (config.debug.externalblobs)
-        DEBUGF("Wrote %d bytes to fd %d", r, write_state->blob_fd);
-      ofs+=r;
+        DEBUGF("Wrote %zd bytes to fd %d", (size_t)r, write_state->blob_fd);
+      ofs += (size_t)r;
     }
   }else{
     if (!write_state->sql_blob)
@@ -782,7 +782,7 @@ static ssize_t rhizome_read_retry(sqlite_retry_state *retry, struct rhizome_read
   // the length.
   size_t bytes_read = 0;
   if (buffer && bufsz && read_state->offset < read_state->length) {
-    bytes_read = read_state->length - read_state->offset;
+    bytes_read = (size_t)(read_state->length - read_state->offset);
     if (bytes_read > bufsz)
       bytes_read = bufsz;
     assert(bytes_read > 0);
@@ -821,7 +821,7 @@ ssize_t rhizome_read(struct rhizome_read *read_state, unsigned char *buffer, siz
     SHA512_Update(&read_state->sha512_context, buffer, bytes_read);
     read_state->hash_offset += bytes_read;
     // if we hash everything and the has doesn't match, we need to delete the payload
-    if (read_state->hash_offset>=read_state->length){
+    if (read_state->hash_offset >= read_state->length){
       rhizome_filehash_t hash_out;
       SHA512_Final(hash_out.binary, &read_state->sha512_context);
       SHA512_End(&read_state->sha512_context, NULL);