diff --git a/src/libs/3rdparty/cplusplus/TranslationUnit.cpp b/src/libs/3rdparty/cplusplus/TranslationUnit.cpp
index 8505deb0bdc..3e51352b147 100644
--- a/src/libs/3rdparty/cplusplus/TranslationUnit.cpp
+++ b/src/libs/3rdparty/cplusplus/TranslationUnit.cpp
@@ -307,7 +307,7 @@ recognize:
 
         if (currentExpanded) {
             QTC_ASSERT(macroOffset != -1 && macroLength != -1, continue);
-            _expansionPositions[_tokens->size() - 1] = std::make_pair(macroOffset, macroLength);
+            _expansionPositions[int(_tokens->size()) - 1] = std::make_pair(macroOffset, macroLength);
         }
     } while (tk.kind());