diff --git a/src/runtime/c/pgf/expr.cxx b/src/runtime/c/pgf/expr.cxx
index 104ea1fb6..b8ea42fc6 100644
--- a/src/runtime/c/pgf/expr.cxx
+++ b/src/runtime/c/pgf/expr.cxx
@@ -1,7 +1,9 @@
 #include "pgf/data.h"
 
 PGF_INTERNAL
-uintptr_t pgf_unmarshall_literal(PgfUnmarshaller *u, PgfLiteral l)
+PgfDBMarshaller db_marshaller;
+
+uintptr_t PgfDBMarshaller::match_lit(PgfUnmarshaller *u, uintptr_t l)
 {
     switch (ref<PgfLiteral>::get_tag(l)) {
     case PgfLiteralInt::tag: {
@@ -18,21 +20,20 @@ uintptr_t pgf_unmarshall_literal(PgfUnmarshaller *u, PgfLiteral l)
     }
 }
 
-PGF_INTERNAL
-uintptr_t pgf_unmarshall_expr(PgfUnmarshaller *u, PgfExpr e)
+uintptr_t PgfDBMarshaller::match_expr(PgfUnmarshaller *u, uintptr_t e)
 {
     switch (ref<PgfExpr>::get_tag(e)) {
     case PgfExprAbs::tag: {
         auto eabs = ref<PgfExprAbs>::untagged(e);
-        uintptr_t body = pgf_unmarshall_expr(u,eabs->body);
+        uintptr_t body = match_expr(u,eabs->body);
         uintptr_t res = u->eabs(eabs->bind_type,&eabs->name,body);
         u->free_ref(body);
         return res;
     }
     case PgfExprApp::tag: {
         auto eapp = ref<PgfExprApp>::untagged(e);
-        uintptr_t fun = pgf_unmarshall_expr(u,eapp->fun);
-        uintptr_t arg = pgf_unmarshall_expr(u,eapp->arg);
+        uintptr_t fun = match_expr(u,eapp->fun);
+        uintptr_t arg = match_expr(u,eapp->arg);
         uintptr_t res = u->eapp(fun,arg);
         u->free_ref(arg);
         u->free_ref(fun);
@@ -40,7 +41,7 @@ uintptr_t pgf_unmarshall_expr(PgfUnmarshaller *u, PgfExpr e)
     }
     case PgfExprLit::tag: {
         auto elit = ref<PgfExprLit>::untagged(e);
-        uintptr_t lit = pgf_unmarshall_literal(u,elit->lit);
+        uintptr_t lit = match_lit(u,elit->lit);
         uintptr_t res = u->elit(lit);
         u->free_ref(lit);
         return res;
@@ -56,8 +57,8 @@ uintptr_t pgf_unmarshall_expr(PgfUnmarshaller *u, PgfExpr e)
 	}
 	case PgfExprTyped::tag: {
         auto etyped = ref<PgfExprTyped>::untagged(e);
-        uintptr_t expr = pgf_unmarshall_expr(u,etyped->expr);
-        uintptr_t type = pgf_unmarshall_type(u,etyped->type);
+        uintptr_t expr = match_expr(u,etyped->expr);
+        uintptr_t type = match_type(u,(uintptr_t) &(*etyped->type));
         uintptr_t res = u->etyped(expr,type);
         u->free_ref(type);
         u->free_ref(expr);
@@ -65,7 +66,7 @@ uintptr_t pgf_unmarshall_expr(PgfUnmarshaller *u, PgfExpr e)
 	}
 	case PgfExprImplArg::tag: {
         auto eimpl = ref<PgfExprImplArg>::untagged(e);
-        uintptr_t expr = pgf_unmarshall_expr(u,eimpl->expr);
+        uintptr_t expr = match_expr(u,eimpl->expr);
         uintptr_t res = u->eimplarg(expr);
         u->free_ref(expr);
         return res;
@@ -76,20 +77,22 @@ uintptr_t pgf_unmarshall_expr(PgfUnmarshaller *u, PgfExpr e)
 }
 
 PGF_INTERNAL
-uintptr_t pgf_unmarshall_type(PgfUnmarshaller *u, PgfType *tp)
+uintptr_t PgfDBMarshaller::match_type(PgfUnmarshaller *u, uintptr_t ty)
 {
+    PgfType *tp = (PgfType *) ty;
+
     PgfTypeHypo *hypos = (PgfTypeHypo *)
         alloca(tp->hypos->len * sizeof(PgfTypeHypo));
     for (size_t i = 0; i < tp->hypos->len; i++) {
         hypos[i].bind_type = tp->hypos->data[i].bind_type;
         hypos[i].cid = &(*tp->hypos->data[i].cid);
-        hypos[i].type = pgf_unmarshall_type(u, tp->hypos->data[i].type);
+        hypos[i].type = match_type(u, (uintptr_t) &(*tp->hypos->data[i].type));
     }
 
     uintptr_t *exprs = (uintptr_t *)
         alloca(tp->exprs->len * sizeof(uintptr_t));
     for (size_t i = 0; i < tp->exprs->len; i++) {
-        exprs[i] = pgf_unmarshall_expr(u, tp->exprs->data[i]);
+        exprs[i] = match_expr(u, tp->exprs->data[i]);
     }
 
     uintptr_t res = u->dtyp(tp->hypos->len, hypos,
diff --git a/src/runtime/c/pgf/expr.h b/src/runtime/c/pgf/expr.h
index bfcfeb143..39064e8db 100644
--- a/src/runtime/c/pgf/expr.h
+++ b/src/runtime/c/pgf/expr.h
@@ -99,14 +99,13 @@ typedef struct {
 	PgfExpr expr;
 } PgfExprProb;
 
-PGF_INTERNAL_DECL
-uintptr_t pgf_unmarshall_literal(PgfUnmarshaller *u, PgfLiteral l);
+struct PgfDBMarshaller : public PgfMarshaller {
+    virtual uintptr_t match_lit(PgfUnmarshaller *u, uintptr_t l);
+    virtual uintptr_t match_expr(PgfUnmarshaller *u, uintptr_t e);
+    virtual uintptr_t match_type(PgfUnmarshaller *u, uintptr_t tp);
+};
 
-PGF_INTERNAL_DECL
-uintptr_t pgf_unmarshall_expr(PgfUnmarshaller *u, PgfExpr e);
-
-PGF_INTERNAL_DECL
-uintptr_t pgf_unmarshall_type(PgfUnmarshaller *u, PgfType *tp);
+extern PGF_INTERNAL_DECL PgfDBMarshaller db_marshaller;
 
 typedef struct PgfBind {
     PgfBindType bind_type;
diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index a68541b4f..4e245d2c6 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -217,7 +217,7 @@ PgfTypeHypo *pgf_category_context(PgfPGF *pgf, PgfText *catname, size_t *n_hypos
     for (size_t i = 0; i < abscat->context->len; i++) {
         hypos[i].bind_type = abscat->context->data[i].bind_type;
         hypos[i].cid = textdup(abscat->context->data[i].cid);
-        hypos[i].type = pgf_unmarshall_type(u, abscat->context->data[i].type);
+        hypos[i].type = db_marshaller.match_type(u, (uintptr_t) &(*abscat->context->data[i].type));
     }
 
     *n_hypos = abscat->context->len;
@@ -283,7 +283,7 @@ uintptr_t pgf_function_type(PgfPGF *pgf, PgfText *funname, PgfUnmarshaller *u)
 	if (absfun == 0)
 		return 0;
 
-	return pgf_unmarshall_type(u, absfun->type);
+	return db_marshaller.match_type(u, (uintptr_t) &(*absfun->type));
 }
 
 PGF_API