diff --git a/CHANGES b/CHANGES
index 14e6a610bd..2e032f2f47 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+5938.	[bug]		An integer type overflow could cause an assertion
+			failure when freeing memory. [GL #3483]
+
 5936.	[bug]		Don't enable serve-stale for lookups that error because
 			it is a duplicate query or a query that would be
 			dropped. [GL #2982]
diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index bebe0e5c6c..b2e53a31e1 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -414,7 +414,7 @@ mem_getstats(isc_mem_t *ctx, size_t size) {
 static void
 mem_putstats(isc_mem_t *ctx, void *ptr, size_t size) {
 	struct stats *stats = stats_bucket(ctx, size);
-	uint_fast32_t s, g;
+	atomic_size_t s, g;
 
 	UNUSED(ptr);