diff --git a/build-aux/pre-inst-env.in b/build-aux/pre-inst-env.in
index b67dc5e..c8deb2d 100644
--- a/build-aux/pre-inst-env.in
+++ b/build-aux/pre-inst-env.in
@@ -30,7 +30,7 @@ export CUIRASS_DATADIR
 PATH="$abs_top_builddir/bin:$PATH"
 export PATH
 
-GUIX_PACKAGE_PATH="guix${GUIX_PACKAGE_PATH:+:}$GUIX_PACKAGE_PATH"
+GUIX_PACKAGE_PATH="$abs_top_srcdir/guix${GUIX_PACKAGE_PATH:+:}$GUIX_PACKAGE_PATH"
 export GUIX_PACKAGE_PATH
 
 exec "$@"