diff --git a/subst.c b/subst.c
index 3958237..673376b 100644
--- a/subst.c
+++ b/subst.c
@@ -6682,6 +6682,7 @@ pat_subst (string, pat, rep, mflags)
 	    mstr[x] = s[x];
           mstr[mlen] = '\0';
           rstr = strcreplace (rep, '&', mstr, 0);
+          free(mstr);
           rslen = strlen (rstr);
         }
       else