diff --git a/core/rexcode/x86/instructions.odin b/core/rexcode/x86/instructions.odin
index 3ad64f237..9a81900d2 100644
--- a/core/rexcode/x86/instructions.odin
+++ b/core/rexcode/x86/instructions.odin
@@ -30,14 +30,14 @@ Rep :: enum u8 {
 // -----------------------------------------------------------------------------
 
 Instruction :: struct #packed {
-	ops:           [4]Operand `fmt:"v,operand_count`, // 64 bytes
-	mnemonic:      Mnemonic,                          // 2 bytes
-	operand_count: u8,                                // 1 byte
-	flags:         Instruction_Flags,                 // 1 byte
-	length:        u8,                                // 1 byte (filled by decoder, used for iteration)
-	_pad:          [3]u8,                             // 3 bytes
+	ops:           [4]Operand `fmt:"v,operand_count`, // 48 bytes
+	mnemonic:      Mnemonic,                          //  2 bytes
+	operand_count: u8,                                //  1 byte
+	flags:         Instruction_Flags,                 //  1 byte
+	length:        u8,                                //  1 byte (filled by decoder, used for iteration)
+	_:             [11]u8,                            // 11 bytes
 }
-#assert(size_of(Instruction) == 72)
+#assert(size_of(Instruction) == 64)
 
 // -----------------------------------------------------------------------------
 // SECTION: 7.9 Instruction Builder Helpers
diff --git a/core/rexcode/x86/operands.odin b/core/rexcode/x86/operands.odin
index d0634abe2..996664d01 100644
--- a/core/rexcode/x86/operands.odin
+++ b/core/rexcode/x86/operands.odin
@@ -165,9 +165,8 @@ Operand :: struct #packed {
 	kind:  Operand_Kind,
 	size:  u8,           // operand size in bytes (1, 2, 4, 8, 16, 32, 64)
 	flags: Operand_Flags,
-	_:     [4]u8,
 }
-#assert(size_of(Operand) == 16)
+#assert(size_of(Operand) == 12)
 
 // EVEX broadcast mode values for Operand_Flags.broadcast
 // Used for EVEX instructions to broadcast a scalar element to all lanes