diff --git a/src/hnswbuild.c b/src/hnswbuild.c
index ab32b1c..fe259dc 100644
--- a/src/hnswbuild.c
+++ b/src/hnswbuild.c
@@ -678,12 +678,8 @@ HnswSharedMemoryAlloc(Size size, void *state)
 static int
 GetMaxDimensions(Relation index)
 {
-	Oid			typid = TupleDescAttr(index->rd_att, 0)->atttypid;
 	FmgrInfo   *procinfo = HnswOptionalProcInfo(index, HNSW_MAX_DIMS_PROC);
 
-	if (typid == VARBITOID)
-		elog(ERROR, "type not supported for hnsw index");
-
 	if (procinfo == NULL)
 		return HNSW_MAX_DIM;
 
@@ -707,6 +703,9 @@ InitBuildState(HnswBuildState * buildstate, Relation heap, Relation index, Index
 	buildstate->efConstruction = HnswGetEfConstruction(index);
 	buildstate->dimensions = TupleDescAttr(index->rd_att, 0)->atttypmod;
 
+	if (TupleDescAttr(index->rd_att, 0)->atttypid == VARBITOID)
+		elog(ERROR, "type not supported for hnsw index");
+
 	maxDimensions = GetMaxDimensions(index);
 
 	/* Require column to have dimensions to be indexed */