diff --git a/src/libs/cplusplus/LookupContext.cpp b/src/libs/cplusplus/LookupContext.cpp
index 3c60dda6410908fa885089dc45f60a4ed2c2c858..96bd8efda309a0e6efeb8c768b5b6fdf415d70d8 100644
--- a/src/libs/cplusplus/LookupContext.cpp
+++ b/src/libs/cplusplus/LookupContext.cpp
@@ -43,12 +43,14 @@
 
 using namespace CPlusPlus;
 
+QT_BEGIN_NAMESPACE
 uint qHash(const CPlusPlus::LookupItem &key)
 {
     const uint h1 = qHash(key.type().type());
     const uint h2 = qHash(key.lastVisibleSymbol());
     return ((h1 << 16) | (h1 >> 16)) ^ h2;
 }
+QT_END_NAMESPACE
 
 /////////////////////////////////////////////////////////////////////
 // LookupContext
diff --git a/src/libs/cplusplus/LookupContext.h b/src/libs/cplusplus/LookupContext.h
index a5aeb69b174dd1504cf68e961428cab22832dab2..3eca2fce3152c6d187943bfc5e1fdd743257c1ee 100644
--- a/src/libs/cplusplus/LookupContext.h
+++ b/src/libs/cplusplus/LookupContext.h
@@ -231,7 +231,9 @@ private:
 } // end of namespace CPlusPlus
 
 
+QT_BEGIN_NAMESPACE
 uint qHash(const CPlusPlus::LookupItem &result);
+QT_END_NAMESPACE
 
 
 #endif // CPLUSPLUS_LOOKUPCONTEXT_H