diff --git a/jOOQ/src/main/java/org/jooq/impl/AbstractAggregateFunction.java b/jOOQ/src/main/java/org/jooq/impl/AbstractAggregateFunction.java
index d6d9bd2361..66b79c7fe0 100644
--- a/jOOQ/src/main/java/org/jooq/impl/AbstractAggregateFunction.java
+++ b/jOOQ/src/main/java/org/jooq/impl/AbstractAggregateFunction.java
@@ -323,6 +323,7 @@ implements
      */
     final DataType<? extends Number> d(Context<?> ctx) {
         switch (ctx.family()) {
+            case FIREBIRD:
             case HSQLDB:
             case SQLITE:
                 return DOUBLE;