diff --git a/pkgs/development/libraries/qt-6/modules/qtbase.nix b/pkgs/development/libraries/qt-6/modules/qtbase.nix
index d539abff5130..ae89c223d2df 100644
--- a/pkgs/development/libraries/qt-6/modules/qtbase.nix
+++ b/pkgs/development/libraries/qt-6/modules/qtbase.nix
@@ -269,7 +269,7 @@ stdenv.mkDerivation rec {
     moveToOutput libexec "$dev"
 
     # fixup .pc file (where to find 'moc' etc.)
-    if [ -d "$dev/lib/pkgconfig" ]; then
+    if [ -f "$dev/lib/pkgconfig/Qt6Core.pc" ]; then
       sed -i "$dev/lib/pkgconfig/Qt6Core.pc" \
         -e "/^bindir=/ c bindir=$dev/bin"
     fi
@@ -277,7 +277,9 @@ stdenv.mkDerivation rec {
     patchShebangs $out $dev
 
     # QTEST_ASSERT and other macros keeps runtime reference to qtbase.dev
-    substituteInPlace "$dev/include/QtTest/qtestassert.h" --replace "__FILE__" "__BASE_FILE__"
+    if [ -f "$dev/include/QtTest/qtestassert.h" ]; then
+      substituteInPlace "$dev/include/QtTest/qtestassert.h" --replace "__FILE__" "__BASE_FILE__"
+    fi
   '';
 
   dontStrip = debugSymbols;