diff --git a/src/runtime/c/pgf/expr.h b/src/runtime/c/pgf/expr.h
index 22a20c160..d5acdadab 100644
--- a/src/runtime/c/pgf/expr.h
+++ b/src/runtime/c/pgf/expr.h
@@ -93,7 +93,7 @@ typedef struct {
 	PgfExpr expr;
 } PgfExprProb;
 
-struct PgfDBMarshaller : public PgfMarshaller {
+struct PGF_INTERNAL_DECL PgfDBMarshaller : public PgfMarshaller {
     virtual object match_lit(PgfUnmarshaller *u, PgfLiteral l);
     virtual object match_expr(PgfUnmarshaller *u, PgfExpr e);
     virtual object match_type(PgfUnmarshaller *u, PgfType ty);