diff --git a/pkgs/development/libraries/qt-5/hooks/qmake-hook.sh b/pkgs/development/libraries/qt-5/hooks/qmake-hook.sh
index 17d3db65849..eef2c7d24df 100644
--- a/pkgs/development/libraries/qt-5/hooks/qmake-hook.sh
+++ b/pkgs/development/libraries/qt-5/hooks/qmake-hook.sh
@@ -10,6 +10,11 @@ qmakeConfigurePhase() {
           NIX_OUTPUT_PLUGIN=${!outputBin}/${qtPluginPrefix:?} \
           $qmakeFlags
 
+    if ! [[ -v enableParallelBuilding ]]; then
+        enableParallelBuilding=1
+        echo "qmake: enabled parallel building"
+    fi
+
     runHook postConfigure
 }