diff --git a/core/cpu.c b/core/cpu.c
index 4f334f5..261ac59 100644
--- a/core/cpu.c
+++ b/core/cpu.c
@@ -880,7 +880,7 @@ static int cpuFloatCommon(VB *sim, double value, int32_t *bits) {
 /* Test whether a floating-point register value is a reserved operand */
 static int cpuFloatReservedOne(int32_t bits) {
     int32_t e = bits >> 23 & 0xFF;
-    return e ? (bits & 0x7FFFFFFF) != 0 : e == 0xFF;
+    return e == 0 ? (bits & 0x7FFFFFFF) != 0 : e == 0xFF;
 }
 
 /* Test whether floating-point register values are reserved operands */