diff --git a/src/mos6502.bits.c b/src/mos6502.bits.c
index 829201d..7063410 100644
--- a/src/mos6502.bits.c
+++ b/src/mos6502.bits.c
@@ -38,7 +38,7 @@ DEFINE_INST(asl)
 
     MOS_CHECK_NZ(result);
     cpu->P &= ~MOS_CARRY;
-    if ((oper << 1) > 0xff) {
+    if (oper & 0x80) {
         cpu->P |= MOS_CARRY;
     }