diff --git a/contrib/pgstattuple/pgstatindex.c b/contrib/pgstattuple/pgstatindex.c
index c0ac1ae5bfb..509e31f1a85 100644
--- a/contrib/pgstattuple/pgstatindex.c
+++ b/contrib/pgstattuple/pgstatindex.c
@@ -377,9 +377,17 @@ pgstatindex(PG_FUNCTION_ARGS)
 		values[j] = palloc(32);
 		snprintf(values[j++], 32, "%d", indexStat.deleted_pages);
 		values[j] = palloc(32);
-		snprintf(values[j++], 32, "%.2f", 100.0 - (float) indexStat.free_space / (float) indexStat.max_avail * 100.0);
+		if (indexStat.max_avail > 0)
+			snprintf(values[j++], 32, "%.2f",
+					 100.0 - (double) indexStat.free_space / (double) indexStat.max_avail * 100.0);
+		else
+			snprintf(values[j++], 32, "NaN");
 		values[j] = palloc(32);
-		snprintf(values[j++], 32, "%.2f", (float) indexStat.fragments / (float) indexStat.leaf_pages * 100.0);
+		if (indexStat.leaf_pages > 0)
+			snprintf(values[j++], 32, "%.2f",
+					 (double) indexStat.fragments / (double) indexStat.leaf_pages * 100.0);
+		else
+			snprintf(values[j++], 32, "NaN");
 
 		tuple = BuildTupleFromCStrings(TupleDescGetAttInMetadata(tupleDesc),
 									   values);