diff --git a/010---vm.cc b/010---vm.cc
index a0724760c..472990a0e 100644
--- a/010---vm.cc
+++ b/010---vm.cc
@@ -108,7 +108,7 @@ struct vma {
   uint8_t& data(uint32_t a) {
     assert(match(a));
     uint32_t result_index = a-start;
-    if (_data.size() <= result_index) {
+    if (_data.size() <= result_index+/*largest word size that can be accessed in one instruction*/sizeof(int)) {
       const int align = 0x1000;
       uint32_t result_size = result_index + 1;  // size needed for result_index to be valid
       uint32_t new_size = align_upwards(result_size, align);
diff --git a/013direct_addressing.cc b/013direct_addressing.cc
index 38e006659..729b4d08e 100644
--- a/013direct_addressing.cc
+++ b/013direct_addressing.cc
@@ -986,7 +986,7 @@ case 0x89: {  // copy r32 to r/m32
   const uint8_t rsrc = (modrm>>3)&0x7;
   trace(Callstack_depth+1, "run") << "copy " << rname(rsrc) << " to r/m32" << end();
   int32_t* dest = effective_address(modrm);
-  *dest = Reg[rsrc].i;
+  *dest = Reg[rsrc].i;  // Write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well.
   trace(Callstack_depth+1, "run") << "storing 0x" << HEXWORD << *dest << end();
   break;
 }
diff --git a/014indirect_addressing.cc b/014indirect_addressing.cc
index 9c50c129a..19d4d5091 100644
--- a/014indirect_addressing.cc
+++ b/014indirect_addressing.cc
@@ -818,7 +818,7 @@ case 0x8f: {  // pop stack into r/m32
     case 0: {
       trace(Callstack_depth+1, "run") << "pop into r/m32" << end();
       int32_t* dest = effective_address(modrm);
-      *dest = pop();
+      *dest = pop();  // Write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well.
       break;
     }
   }
diff --git a/015immediate_addressing.cc b/015immediate_addressing.cc
index c264d5d3d..a2923b7ad 100644
--- a/015immediate_addressing.cc
+++ b/015immediate_addressing.cc
@@ -1235,7 +1235,7 @@ case 0xc7: {  // copy imm32 to r32
   int32_t* dest = effective_address(modrm);
   const int32_t src = next32();
   trace(Callstack_depth+1, "run") << "imm32 is 0x" << HEXWORD << src << end();
-  *dest = src;
+  *dest = src;  // Write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well.
   break;
 }
 
diff --git a/021byte_addressing.cc b/021byte_addressing.cc
index a0b36776d..36287e380 100644
--- a/021byte_addressing.cc
+++ b/021byte_addressing.cc
@@ -68,7 +68,7 @@ case 0x88: {  // copy r8 to r/m8
   // use unsigned to zero-extend 8-bit value to 32 bits
   uint8_t* dest = reinterpret_cast<uint8_t*>(effective_byte_address(modrm));
   const uint8_t* src = reg_8bit(rsrc);
-  *dest = *src;
+  *dest = *src;  // Read/write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well.
   trace(Callstack_depth+1, "run") << "storing 0x" << HEXBYTE << NUM(*dest) << end();
   break;
 }
@@ -108,7 +108,7 @@ case 0x8a: {  // copy r/m8 to r8
   const uint8_t* src = reinterpret_cast<uint8_t*>(effective_byte_address(modrm));
   uint8_t* dest = reg_8bit(rdest);
   trace(Callstack_depth+1, "run") << "storing 0x" << HEXBYTE << NUM(*src) << end();
-  *dest = *src;
+  *dest = *src;  // Read/write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well.
   const uint8_t rdest_32bit = rdest & 0x3;
   trace(Callstack_depth+1, "run") << rname(rdest_32bit) << " now contains 0x" << HEXWORD << Reg[rdest_32bit].u << end();
   break;
@@ -170,7 +170,7 @@ case 0xc6: {  // copy imm8 to r/m8
   }
   // use unsigned to zero-extend 8-bit value to 32 bits
   uint8_t* dest = reinterpret_cast<uint8_t*>(effective_byte_address(modrm));
-  *dest = src;
+  *dest = src;  // Write multiple elements of vector<uint8_t> at once. Assumes sizeof(int) == 4 on the host as well.
   trace(Callstack_depth+1, "run") << "storing 0x" << HEXBYTE << NUM(*dest) << end();
   break;
 }