diff --git a/third_party/libxml/src/parserInternals.c b/third_party/libxml/src/parserInternals.c
index bfc778ac1f77..286fdcea9760 100644
--- src/parserInternals.c
+++ src/parserInternals.c
@@ -1369,8 +1369,13 @@ xmlNewInputStream(xmlParserCtxtPtr ctxt) {
      * should not happen while parsing which is the situation where
      * the id is actually needed.
      */
-    if (ctxt != NULL)
+    if (ctxt != NULL) {
+        if (ctxt->input_id >= INT_MAX) {
+            xmlErrMemory(ctxt, "Input ID overflow\n");
+            return(NULL);
+        }
         input->id = ctxt->input_id++;
+    }
 
     return(input);
 }