diff --git a/src/box/memtx_rtree.c b/src/box/memtx_rtree.c
index d5c2ee90ac34f7038e2a8618371b3a799f8e4c10..d52bd4d7124dbc60e8f4285296b9a21e3fac9ca9 100644
--- a/src/box/memtx_rtree.c
+++ b/src/box/memtx_rtree.c
@@ -324,7 +324,7 @@ memtx_rtree_index_new(struct memtx_engine *memtx, struct index_def *def)
 	if (def->opts.dimension < 1 ||
 	    def->opts.dimension > RTREE_MAX_DIMENSION) {
 		diag_set(UnsupportedIndexFeature, def,
-			 tt_sprintf("dimension (%u): must belong to "
+			 tt_sprintf("dimension (%lld): must belong to "
 				    "range [%u, %u]", def->opts.dimension,
 				    1, RTREE_MAX_DIMENSION));
 		return NULL;