diff --git a/src/plugins/qmldesigner/components/connectioneditor/connectionmodel.cpp b/src/plugins/qmldesigner/components/connectioneditor/connectionmodel.cpp
index 7f0db656005..838e1d587dd 100644
--- a/src/plugins/qmldesigner/components/connectioneditor/connectionmodel.cpp
+++ b/src/plugins/qmldesigner/components/connectioneditor/connectionmodel.cpp
@@ -1815,7 +1815,7 @@ bool ConditionListModel::operatorAllowed(int cursorPosition)
 
     int tokenIdx = cursorPosition - 1;
 
-    if (tokenIdx >= 0 && m_tokens[tokenIdx].type != Operator)
+    if (tokenIdx >= 0 && tokenIdx < m_tokens.length() && m_tokens[tokenIdx].type != Operator)
         return true;
 
     return false;