PyOS_CheckStack() returns 1 when failing, not -1.
diff --git a/Objects/object.c b/Objects/object.c
index 1f02aae..9f73cd3 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -402,7 +402,7 @@
 	int result;
 
 #if defined(USE_STACKCHECK)
-	if (PyOS_CheckStack() < 0) {
+	if (PyOS_CheckStack()) {
 		PyErr_SetString(PyExc_MemoryError, "Stack overflow");
         return -1;
 	}