diff --git a/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabase.java b/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabase.java
index ad8af11bcb4911ae5f5125c896d1b2f6ca222f70..851c17bb90dbbf94c6df457ab239c5461d5807e2 100644
--- a/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabase.java
+++ b/pgjdbc/src/main/java/org/postgresql/jdbc/PgDatabase.java
@@ -45,6 +45,9 @@ public class PgDatabase {
         String extensionDolphin = getDolphin("select count(1) from pg_extension where extname = 'dolphin';");
         int dolphinNum = Integer.parseInt(extensionDolphin);
         String compatibility = getDolphin("show dolphin.b_compatibility_mode;");
+        if (compatibility == null || compatibility.isEmpty()) {
+            compatibility = "OFF";
+        }
         CompatibilityEnum compatibilityEnum = CompatibilityEnum.valueOf(compatibility.toUpperCase(Locale.ROOT));
 
         if (dolphinNum > 0 && CompatibilityEnum.ON.equals(compatibilityEnum)) {