diff --git a/src/tuxpaint.c b/src/tuxpaint.c
index 30c6b948a..b62008371 100644
--- a/src/tuxpaint.c
+++ b/src/tuxpaint.c
@@ -1190,6 +1190,9 @@ static void do_locale_option(const char * const arg)
   char *str = malloc(len);
   snprintf(str, len, "LANG=%s", arg);
   putenv(str);
+  // We leak "str" because it can not be freed. It is now part
+  // of the environment. If it were local, the environment would
+  // get corrupted.
   setlocale(LC_ALL, ""); /* use arg ? */
 }