diff --git a/src/codegen_timing_pentium.c b/src/codegen_timing_pentium.c
index a142024..4194e3a 100644
--- a/src/codegen_timing_pentium.c
+++ b/src/codegen_timing_pentium.c
@@ -962,7 +962,7 @@ void codegen_timing_pentium_prefix(uint8_t prefix, uint32_t fetchdat)
                 last_prefix = prefix;
                 return;
         }
-        if (prefix == 0x0f && (opcode & 0xf0) == 0x80)
+        if (prefix == 0x0f && (fetchdat & 0xf0) == 0x80)
         {
                 /*On Pentium 0fh prefix is 'free' when used on conditional jumps*/
                 last_prefix = prefix;