diff --git a/lib/xmlparse.c b/lib/xmlparse.c
index c4f3ffc..ca29328 100644
--- a/lib/xmlparse.c
+++ b/lib/xmlparse.c
@@ -2047,6 +2047,11 @@
     keep = (int)EXPAT_SAFE_PTR_DIFF(parser->m_bufferPtr, parser->m_buffer);
     if (keep > XML_CONTEXT_BYTES)
       keep = XML_CONTEXT_BYTES;
+    /* Detect and prevent integer overflow */
+    if (keep > INT_MAX - neededSize) {
+      parser->m_errorCode = XML_ERROR_NO_MEMORY;
+      return NULL;
+    }
     neededSize += keep;
 #endif  /* defined XML_CONTEXT_BYTES */
     if (neededSize <= EXPAT_SAFE_PTR_DIFF(parser->m_bufferLim, parser->m_buffer)) {