diff --git a/src/ecmascript/ecmascript.c b/src/ecmascript/ecmascript.c
index 1bce7ec01..fb513d12c 100644
--- a/src/ecmascript/ecmascript.c
+++ b/src/ecmascript/ecmascript.c
@@ -100,6 +100,10 @@ ecmascript_put_interpreter(struct ecmascript_interpreter *interpreter)
 {
 	assert(interpreter);
 	assert(interpreter->backend_nesting == 0);
+	/* If the assertion fails, it is better to leak the
+	 * interpreter than to corrupt memory.  */
+	if_assert_failed return;
+
 	spidermonkey_put_interpreter(interpreter);
 	free_string_list(&interpreter->onload_snippets);
 	mem_free(interpreter);