diff --git a/pkgs/development/python-modules/generic/wrap.sh b/pkgs/development/python-modules/generic/wrap.sh
index 33b9a06f6080..b6d2a66afff6 100644
--- a/pkgs/development/python-modules/generic/wrap.sh
+++ b/pkgs/development/python-modules/generic/wrap.sh
@@ -37,6 +37,9 @@ wrapPythonProgramsIn() {
             # dont wrap EGG-INFO scripts since they are called from python
             if echo "$f" | grep -qv EGG-INFO/scripts; then
                 echo "wrapping \`$f'..."
+                # The magicalSedExpression will invoke a "$(basename "$f")", so
+                # if you change $f to something else, be sure to also change it
+                # in pkgs/top-level/python-packages.nix!
                 sed -i "$f" -re '@magicalSedExpression@'
                 # wrapProgram creates the executable shell script described
                 # above. The script will set PYTHONPATH and PATH variables.!
diff --git a/pkgs/top-level/python-packages.nix b/pkgs/top-level/python-packages.nix
index d2aecc941581..3e9e07361dc6 100644
--- a/pkgs/top-level/python-packages.nix
+++ b/pkgs/top-level/python-packages.nix
@@ -68,7 +68,7 @@ let
           /\\$/{N;br}
           /__future__|^ *(#.*)?$/{n;br}
           ${concatImapStrings mkStringSkipper quoteVariants}
-          /^ *[^# ]/i import sys; sys.argv[0] = '"'$(basename "$i")'"'
+          /^ *[^# ]/i import sys; sys.argv[0] = '"'$(basename "$f")'"'
         }
       '';
     }