diff --git a/pandaapp/Package.pp b/pandaapp/Package.pp
index de2daff3af..0cfb9106e5 100644
--- a/pandaapp/Package.pp
+++ b/pandaapp/Package.pp
@@ -42,8 +42,8 @@
     #error You seem to be attached to some trees, but not PANDAAPP!
   #endif
 #else
-  #defer PANDAAPP_INSTALL $[INSTALL_DIR]
-  #defer PANDAAPP_INSTALL_OTHER $[INSTALL_DIR]
+  #defer PANDAAPP_INSTALL $[unixfilename $[INSTALL_DIR]]
+  #defer PANDAAPP_INSTALL_OTHER $[unixfilename $[INSTALL_DIR]]
 #endif
 
 // Also get the PANDATOOL Package file and everything that includes.