diff --git a/libraries/virglrenderer/virglrenderer.SlackBuild b/libraries/virglrenderer/virglrenderer.SlackBuild
index 117516db0c..bc74d310ef 100644
--- a/libraries/virglrenderer/virglrenderer.SlackBuild
+++ b/libraries/virglrenderer/virglrenderer.SlackBuild
@@ -83,8 +83,8 @@ cd build
     --mandir=/usr/man \
     --prefix=/usr \
     --sysconfdir=/etc
-  ninja
-  DESTDIR=$PKG ninja install
+  "${NINJA:=ninja}"
+  DESTDIR=$PKG $NINJA install
 cd ..
 
 find $PKG -print0 | xargs -0 file | grep -e "executable" -e "shared object" | grep ELF \