diff --git a/src/libs/cplusplus/CppDocument.cpp b/src/libs/cplusplus/CppDocument.cpp
index 3dc8eeb8284..c347e5f431c 100644
--- a/src/libs/cplusplus/CppDocument.cpp
+++ b/src/libs/cplusplus/CppDocument.cpp
@@ -340,9 +340,10 @@ QStringList Document::includedFiles() const
     return files;
 }
 
+// This assumes to be called with a QDir::cleanPath cleaned fileName.
 void Document::addIncludeFile(const QString &fileName, unsigned line)
 {
-    _includes.append(Include(QDir::cleanPath(fileName), line));
+    _includes.append(Include(fileName, line));
 }
 
 void Document::appendMacro(const Macro &macro)
diff --git a/src/libs/cplusplus/FastPreprocessor.cpp b/src/libs/cplusplus/FastPreprocessor.cpp
index 1eff7ff3b98..9fd03a889cf 100644
--- a/src/libs/cplusplus/FastPreprocessor.cpp
+++ b/src/libs/cplusplus/FastPreprocessor.cpp
@@ -30,6 +30,7 @@
 #include "FastPreprocessor.h"
 #include <Literals.h>
 #include <TranslationUnit.h>
+#include <QDir>
 
 using namespace CPlusPlus;
 
@@ -62,7 +63,9 @@ QByteArray FastPreprocessor::run(Document::Ptr newDoc, const QString &source)
 void FastPreprocessor::sourceNeeded(unsigned line, QString &fileName, IncludeType)
 {
     Q_ASSERT(_currentDoc);
-    _currentDoc->addIncludeFile(fileName, line);
+    // CHECKME: Is that cleanName needed?
+    QString cleanName = QDir::cleanPath(fileName);
+    _currentDoc->addIncludeFile(cleanName, line);
 
     mergeEnvironment(fileName);
 }