diff --git a/src/compiler.cpp b/src/compiler.cpp
index 65e8218922..d3aa2751cf 100644
--- a/src/compiler.cpp
+++ b/src/compiler.cpp
@@ -1592,11 +1592,12 @@ appendMove(Context* c, BinaryOperation type, unsigned size, Value* src,
 
 class CompareEvent: public Event {
  public:
-  CompareEvent(Context* c, unsigned size, Value* first, Value* second):
+  CompareEvent(Context* c, unsigned size, Value* first, Value* second,
+               Site* firstTarget, Site* secondTarget):
     Event(c), size(size), first(first), second(second)
   {
-    addRead(c, first, size, 0);
-    addRead(c, second, size, 0);
+    addRead(c, first, size, firstTarget);
+    addRead(c, second, size, secondTarget);
   }
 
   virtual void compile(Context* c) {
@@ -1618,12 +1619,23 @@ class CompareEvent: public Event {
 void
 appendCompare(Context* c, unsigned size, Value* first, Value* second)
 {
+  VirtualSite* firstTarget = virtualSite(c);
+  VirtualSite* secondTarget = virtualSite(c);
+  uintptr_t procedure;
+
+  c->assembler->plan(Compare, size,
+                     &(firstTarget->typeMask), &(firstTarget->registerMask),
+                     &(secondTarget->typeMask), &(secondTarget->registerMask),
+                     &procedure);
+
+  assert(c, procedure == 0); // todo
+
   if (DebugAppend) {
     fprintf(stderr, "appendCompare\n");
   }
 
   new (c->zone->allocate(sizeof(CompareEvent)))
-    CompareEvent(c, size, first, second);
+    CompareEvent(c, size, first, second, firstTarget, secondTarget);
 }
 
 void
diff --git a/src/x86.cpp b/src/x86.cpp
index c45ef7ea44..efa90b52a7 100644
--- a/src/x86.cpp
+++ b/src/x86.cpp
@@ -1928,7 +1928,7 @@ class MyAssembler: public Assembler {
                     uint64_t* aRegisterMask, uint8_t* bTypeMask,
                     uint64_t* bRegisterMask, uintptr_t* procedure)
   {
-    *aTypeMask = ~static_cast<uint8_t>(0);
+    *aTypeMask = ~0;
     *aRegisterMask = ~static_cast<uint64_t>(0);
 
     *bTypeMask = (1 << RegisterOperand) | (1 << MemoryOperand);
@@ -1937,6 +1937,15 @@ class MyAssembler: public Assembler {
     *procedure = 0;
 
     switch (op) {
+    case Compare:
+      if (BytesPerWord == 8 and size != 8) {
+        *aTypeMask = ~(1 << MemoryOperand);
+        *bTypeMask = ~(1 << MemoryOperand);
+      } else {
+        *bTypeMask = ~0;
+      }
+      break;
+
     case Move:
       if (BytesPerWord == 4 and size == 1) {
         const uint32_t mask
@@ -1965,7 +1974,7 @@ class MyAssembler: public Assembler {
 
     case Divide:
       if (BytesPerWord == 4 and size == 8) {
-        *bTypeMask = ~static_cast<uint8_t>(0);
+        *bTypeMask = ~0;
         *procedure = reinterpret_cast<uintptr_t>(divideLong);        
       } else {
         *aRegisterMask = ~((1 << rax) | (1 << rdx));
@@ -1975,7 +1984,7 @@ class MyAssembler: public Assembler {
 
     case Remainder:
       if (BytesPerWord == 4 and size == 8) {
-        *bTypeMask = ~static_cast<uint8_t>(0);
+        *bTypeMask = ~0;
         *procedure = reinterpret_cast<uintptr_t>(moduloLong);
       } else {
         *aRegisterMask = ~((1 << rax) | (1 << rdx));