diff --git a/vm/cpu-ppc.S b/vm/cpu-ppc.S
index 1071d8b8a9..40f2521e50 100644
--- a/vm/cpu-ppc.S
+++ b/vm/cpu-ppc.S
@@ -43,7 +43,7 @@ DEF(void,primitive_fixnum_multiply,(void *vm)):
 	stw r6,0(DS_REG)
 	blr
 multiply_overflow:
-	srawi r4,r4,3
+	srawi r4,r4,4
 	b MANGLE(overflow_fixnum_multiply)
 	
 /* Note that the XT is passed to the quotation in r11 */
diff --git a/vm/cpu-x86.S b/vm/cpu-x86.S
index 706369876f..846300120d 100644
--- a/vm/cpu-x86.S
+++ b/vm/cpu-x86.S
@@ -33,7 +33,7 @@ DEF(void,primitive_fixnum_multiply,(void *myvm)):
 	pop ARG2
 	ret
 multiply_overflow:
-	sar $3,ARITH_TEMP_1
+	sar $4,ARITH_TEMP_1
 	mov ARITH_TEMP_1,ARG0
 	mov ARITH_TEMP_2,ARG1
 	pop ARG2