diff --git a/cpu.c b/cpu.c
index 4aeaaf6..3bbfc42 100644
--- a/cpu.c
+++ b/cpu.c
@@ -120,7 +120,7 @@ adc(uint8_t arg)
 
 	regs.status.carry = sum > 0xFF;
 	/* overflow flag formula: https://stackoverflow.com/a/29224684 */
-	regs.status.overflow = ~(regs.a ^ arg) & (regs.a ^ sum) & 0x80;
+	regs.status.overflow = (~(regs.a ^ arg) & (regs.a ^ sum) & 0x80) > 0;
 	STATUS_UPDATE_ZERO(regs.a);
 	STATUS_UPDATE_NEGATIVE(regs.a);
 }