diff --git a/hacking/env-setup.fish b/hacking/env-setup.fish
index 1613baeb14..05fb60672d 100644
--- a/hacking/env-setup.fish
+++ b/hacking/env-setup.fish
@@ -16,7 +16,7 @@ else
         case "$PREFIX_PYTHONPATH*"
         case "*"
             echo "Appending PYTHONPATH"
-            set -gx PYTHONPATH $PREFIX_PYTHONPATH:$PYTHONPATH
+            set -gx PYTHONPATH "$PREFIX_PYTHONPATH:$PYTHONPATH"
     end
 end