diff --git a/src/plugins/qmakeprojectmanager/qmakeparsernodes.cpp b/src/plugins/qmakeprojectmanager/qmakeparsernodes.cpp
index 76f3a08e3af..f7d03e0a3c3 100644
--- a/src/plugins/qmakeprojectmanager/qmakeparsernodes.cpp
+++ b/src/plugins/qmakeprojectmanager/qmakeparsernodes.cpp
@@ -1355,7 +1355,10 @@ static bool evaluateOne(const QmakeEvalInput &input, ProFile *pro,
 
         // We don't increase/decrease m_qmakeGlobalsRefCnt here, because the outer profilereaders keep m_qmakeGlobals alive anyway
         auto bpReader = new QtSupport::ProFileReader(input.qmakeGlobals, input.qmakeVfs); // needs to access m_qmakeGlobals, m_qmakeVfs
-        bpReader->setOutputDir(input.buildDirectory.toString());
+
+        // FIXME: Currently intentional.
+        // Core parts of the ProParser hard-assert on non-local items.
+        bpReader->setOutputDir(input.buildDirectory.path());
         bpReader->setCumulative(cumulative);
         bpReader->setExtraVars(basevars);
         bpReader->setExtraConfigs(basecfgs);
diff --git a/src/plugins/qmakeprojectmanager/qmakeproject.cpp b/src/plugins/qmakeprojectmanager/qmakeproject.cpp
index 212748af514..3babadd0dc7 100644
--- a/src/plugins/qmakeprojectmanager/qmakeproject.cpp
+++ b/src/plugins/qmakeprojectmanager/qmakeproject.cpp
@@ -857,7 +857,9 @@ QtSupport::ProFileReader *QmakeBuildSystem::createProFileReader(const QmakeProFi
 
     auto reader = new QtSupport::ProFileReader(m_qmakeGlobals.get(), m_qmakeVfs);
 
-    reader->setOutputDir(buildDir(qmakeProFile->filePath()).toString());
+    // FIXME: Currently intentional.
+    // Core parts of the ProParser hard-assert on non-local items
+    reader->setOutputDir(buildDir(qmakeProFile->filePath()).path());
 
     return reader;
 }