diff --git a/qmake/generators/makefile.cpp b/qmake/generators/makefile.cpp
--- a/qmake/generators/makefile.cpp
+++ b/qmake/generators/makefile.cpp
@@ -3390,8 +3390,7 @@ MakefileGenerator::writePkgConfigFile()
       << varGlue("QMAKE_PKGCONFIG_CFLAGS", "", " ", " ")
         //      << varGlue("DEFINES","-D"," -D"," ")
          ;
-    if (!project->values("QMAKE_DEFAULT_INCDIRS").contains(includeDir))
-        t << "-I${includedir}";
+    t << "-I${includedir}";
     if (target_mode == TARG_MAC_MODE && project->isActiveConfig("lib_bundle")
         && libDir != QLatin1String("/Library/Frameworks")) {
             t << " -F${libdir}";