diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index d06a8dbb64..7b391042d9 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -547,20 +547,14 @@ mem_create(const char *name, isc_mem_t **ctxp, unsigned int debugging,
 
 static void
 mem_destroy(isc_mem_t *ctx) {
+	REQUIRE(VALID_CONTEXT(ctx));
+
 	isc_refcount_destroy(&ctx->references);
 
 	LOCK(&contextslock);
 	ISC_LIST_UNLINK(contexts, ctx, link);
 	UNLOCK(&contextslock);
 
-	if (ctx->checkfree) {
-		INSIST(isc_mem_inuse(ctx) == 0);
-	}
-
-	ctx->magic = 0;
-
-	INSIST(ISC_LIST_EMPTY(ctx->pools));
-
 #if ISC_MEM_TRACKLINES
 	if (ctx->debuglist != NULL) {
 		for (size_t i = 0; i < DEBUG_TABLE_COUNT; i++) {
@@ -582,6 +576,14 @@ mem_destroy(isc_mem_t *ctx) {
 	}
 #endif /* if ISC_MEM_TRACKLINES */
 
+	if (ctx->checkfree) {
+		INSIST(isc_mem_inuse(ctx) == 0);
+	}
+
+	ctx->magic = 0;
+
+	INSIST(ISC_LIST_EMPTY(ctx->pools));
+
 	free(ctx->name);
 
 	isc_mutex_destroy(&ctx->lock);