diff --git a/src/tcache.c b/src/tcache.c
index be4fb878..e7b970d9 100644
--- a/src/tcache.c
+++ b/src/tcache.c
@@ -123,6 +123,9 @@ tbin_extents_lookup_size_check(tsdn_t *tsdn, cache_bin_t *tbin, szind_t binind,
 		sz_sum -= szind;
 	}
 	if (sz_sum != 0) {
+		malloc_printf("<jemalloc>: size mismatch in thread cache "
+		    "detected, likely caused by sized deallocation bugs by "
+		    "application. Abort.\n");
 		abort();
 	}
 }