diff --git a/mercurial/cext/revlog.c b/mercurial/cext/revlog.c
--- a/mercurial/cext/revlog.c
+++ b/mercurial/cext/revlog.c
@@ -1377,8 +1377,13 @@
 	char *node;
 	int rev;
 
-	if (PyInt_Check(value))
-		return index_get(self, PyInt_AS_LONG(value));
+	if (PyInt_Check(value)) {
+		long arg = PyInt_AS_LONG(value);
+		if (PyErr_Occurred()) {
+			return NULL;
+		}
+		return index_get(self, arg);
+	}
 
 	if (node_check(value, &node) == -1)
 		return NULL;