diff --git a/libavutil/cast5.c b/libavutil/cast5.c
index 63f859886c9cc10576405e6f2b6cb67ae34325b5..2309223022651cb29b0a1ef0ec5ee77c6c6183f7 100644
--- a/libavutil/cast5.c
+++ b/libavutil/cast5.c
@@ -535,6 +535,7 @@ int main(int argc, char** argv)
             }
         }
     }
+    av_free(cs);
     return err;
 }
 #endif