diff --git a/qmake/cachekeys.h b/qmake/cachekeys.h
index 26a95e4f27..2d2fd63951 100644
--- a/qmake/cachekeys.h
+++ b/qmake/cachekeys.h
@@ -29,6 +29,7 @@
 #ifndef CACHEKEYS_H
 #define CACHEKEYS_H
 
+#include "option.h"
 #include "project.h"
 #include <qstring.h>
 #include <qstringlist.h>
diff --git a/qmake/project.cpp b/qmake/project.cpp
index 15870395ae..066ac1838f 100644
--- a/qmake/project.cpp
+++ b/qmake/project.cpp
@@ -28,6 +28,7 @@
 
 #include "project.h"
 
+#include "cachekeys.h"
 #include "option.h"
 #include <qmakeevaluator_p.h>
 
@@ -52,8 +53,10 @@ QMakeProject::QMakeProject(QMakeProject *p)
 
 bool QMakeProject::boolRet(VisitReturn vr)
 {
-    if (vr == ReturnError)
+    if (vr == ReturnError) {
+        qmakeClearCaches();
         exit(3);
+    }
     Q_ASSERT(vr == ReturnTrue || vr == ReturnFalse);
     return vr != ReturnFalse;
 }