diff --git a/test/fixedbugs/issue11656.go b/test/fixedbugs/issue11656.go
index 565e796ed0..93e18225c1 100644
--- a/test/fixedbugs/issue11656.go
+++ b/test/fixedbugs/issue11656.go
@@ -65,6 +65,8 @@ func f(n int) {
 		binary.BigEndian.PutUint32(ill, 0x00000034) // trap
 	case "mips64le":
 		binary.LittleEndian.PutUint32(ill, 0x00000034) // trap
+	case "s390x":
+		binary.BigEndian.PutUint32(ill, 0) // undefined instruction
 	default:
 		// Just leave it as 0 and hope for the best.
 	}