diff --git a/src/compiler/GF/Compile/Compute/Concrete.hs b/src/compiler/GF/Compile/Compute/Concrete.hs
index a4c30bacd..f24582c6f 100644
--- a/src/compiler/GF/Compile/Compute/Concrete.hs
+++ b/src/compiler/GF/Compile/Compute/Concrete.hs
@@ -50,6 +50,7 @@ data Value s
   | VMeta (Thunk s) (Env s) [Thunk s]
   | VGen  {-# UNPACK #-} !Int [Thunk s]
   | VClosure (Env s) Term
+  | VProd BindType Ident (Value s) (Value s)
   | VRecType [(Label, Value s)]
   | VR [(Label, Thunk s)]
   | VP (Value s) Label [Thunk s]
@@ -79,7 +80,8 @@ eval env (Abs b x t) (v:vs) = eval ((x,v):env) t vs
 eval env (Meta i)       vs  = do tnk <- newMeta i
                                  return (VMeta tnk env vs)
 eval env (ImplArg t)    []  = eval env t []
--- eval env (Prod b x t1 t2)[] = eval env t []
+eval env (Prod b x t1 t2)[] = do v1 <- eval env t1 []
+                                 return (VProd b x v1 (VClosure env (Abs b x t2)))
 eval env (Typed t ty)   vs  = eval env t vs
 eval env (RecType lbls) []  = do lbls <- mapM (\(lbl,ty) -> fmap ((,) lbl) (eval env ty [])) lbls
                                  return (VRecType lbls)
@@ -188,6 +190,10 @@ value2term i (VClosure env (Abs b x t)) = do
   v <- eval ((x,tnk):env) t []
   t <- value2term (i+1) v
   return (Abs b (identS ('v':show i)) t)
+value2term i (VProd b x v1 v2) = do
+  t1 <- value2term i v1
+  t2 <- value2term i v2
+  return (Prod b x t1 t2)
 value2term i (VRecType lbls) = do
   lbls <- mapM (\(lbl,v) -> fmap ((,) lbl) (value2term i v)) lbls
   return (RecType lbls)
diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index 0a6af1cd0..9d3230dff 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -638,8 +638,10 @@ PgfRevision pgf_checkout_revision(PgfDB *db, PgfText *name,
     PGF_API_BEGIN {
         DB_scope scope(db, WRITER_SCOPE);
         ref<PgfPGF> pgf = PgfDB::get_revision(name);
-        Node<PgfPGF>::add_value_ref(pgf);
-        db->ref_count++;
+        if (pgf != 0) {
+            Node<PgfPGF>::add_value_ref(pgf);
+            db->ref_count++;
+        }
         return pgf.as_object();
     } PGF_API_END
 
diff --git a/src/runtime/python/ffi.c b/src/runtime/python/ffi.c
index 4fbf3e07f..4df306b62 100644
--- a/src/runtime/python/ffi.c
+++ b/src/runtime/python/ffi.c
@@ -159,12 +159,18 @@ PyList_AsPgfPrintContext(PyObject *pylist)
             PyErr_SetString(PyExc_TypeError, "variable argument in context must be a string");
             return NULL;
         }
-        PgfText *input = PyUnicode_AsPgfText(item);
 
-        // TODO a better way to copy into this->name?
-        PgfPrintContext *this = (PgfPrintContext *)PyMem_RawMalloc(sizeof(PgfPrintContext *) + sizeof(PgfText) + input->size + 1);
+        if (PyUnicode_READY(item) != 0) {
+            return NULL;
+        }
+
+        Py_ssize_t size;
+        const char *enc = PyUnicode_AsUTF8AndSize(item, &size);
+
+        PgfPrintContext *this = (PgfPrintContext *)PyMem_RawMalloc(sizeof(PgfPrintContext) + size + 1);
         this->next = ctxt;
-        memcpy(&this->name, input, sizeof(PgfText)+input->size+1);
+        this->name.size = size;
+        memcpy(&this->name.text, enc, size+1);
         ctxt = this;
     }
 
@@ -291,6 +297,7 @@ lint(PgfUnmarshaller *this, size_t size, uintmax_t *v)
             Py_DECREF(i);
             i = tmp;
         }
+        Py_DECREF(intShifter);
         if (PyErr_Occurred()) {
             return 0;
         }
@@ -363,42 +370,61 @@ match_lit(PgfMarshaller *this, PgfUnmarshaller *u, PgfLiteral lit)
     PyObject *pyobj = (PyObject *)lit;
 
     if (PyLong_Check(pyobj)) {
-        PyObject *intShifter = PyLong_FromUnsignedLong(pow(10, floor(log10(ULONG_MAX))));
+        PyObject *intShifter = PyLong_FromUnsignedLong(LINT_BASE);
 
         // determine size
         size_t size = 1;
-        PyObject *x = PyNumber_Absolute(PyNumber_Long(pyobj)); // make a copy, ignore sign
+        PyObject *x = PyNumber_Absolute(pyobj); // make a copy, ignore sign
         while (PyObject_RichCompareBool(x, intShifter, Py_GE) == 1) {
             size++;
-            x = PyNumber_FloorDivide(x, intShifter);
+            PyObject *tmp = PyNumber_FloorDivide(x, intShifter);
+            Py_DECREF(x);
+            x = tmp;
         }
+        Py_DECREF(x);
 
         // chop up into chunks, always positive
-        bool isPos = PyObject_RichCompareBool(pyobj, PyLong_FromLong(0), Py_GE) == 1;
-        x = PyNumber_Absolute(PyNumber_Long(pyobj)); // make a copy, ignore sign
+        PyObject *zero = PyLong_FromLong(0);
+        bool isPos = PyObject_RichCompareBool(pyobj, zero, Py_GE) == 1;
+        Py_DECREF(zero);
+        x = PyNumber_Absolute(pyobj); // make a copy, ignore sign
         uintmax_t *i = PyMem_RawMalloc(sizeof(uintmax_t)*size); // TODO when does this get freed?
         for (int n = size-1; n > 0; n--) {
             PyObject *rem = PyNumber_Remainder(x, intShifter);
             i[n] = PyLong_AsUnsignedLong(rem);
-            x = PyNumber_FloorDivide(x, intShifter);
+            Py_DECREF(rem);
+            PyObject *tmp = PyNumber_FloorDivide(x, intShifter);
+            Py_DECREF(x);
+            x = tmp;
         }
 
+        Py_DECREF(intShifter);
+
         // first chunk, re-applying polarity
         if (isPos)
             i[0] = PyLong_AsLong(x);
         else
-            i[0] = PyLong_AsLong(PyNumber_Negative(x));
+            i[0] = -PyLong_AsLong(x);
+
+        Py_DECREF(x);
 
         if (PyErr_Occurred()) {
             return 0;
         }
-        return u->vtbl->lint(u, size, i);
+
+        object res = u->vtbl->lint(u, size, i);
+
+        PyMem_RawFree(i);
+
+        return res;
     } else if (PyFloat_Check(pyobj)) {
         double d = PyFloat_AsDouble(pyobj);
         return u->vtbl->lflt(u, d);
     } else if (PyUnicode_Check(pyobj)) {
         PgfText *t = PyUnicode_AsPgfText(pyobj);
-        return u->vtbl->lstr(u, t);
+        object res = u->vtbl->lstr(u, t);
+        FreePgfText(t);
+        return res;
     } else {
         PyErr_SetString(PyExc_TypeError, "unable to match on literal");
         return 0;
@@ -413,7 +439,10 @@ match_expr(PgfMarshaller *this, PgfUnmarshaller *u, PgfExpr expr)
     if (PyObject_TypeCheck(pyobj, &pgf_ExprAbsType)) {
         ExprAbsObject *eabs = (ExprAbsObject *)expr;
         long bt = eabs->bind_type == Py_True ? 0 : 1;
-        return u->vtbl->eabs(u, bt, PyUnicode_AsPgfText(eabs->name), (PgfExpr) eabs->body);
+        PgfText *name = PyUnicode_AsPgfText(eabs->name);
+        object res = u->vtbl->eabs(u, bt, name, (PgfExpr) eabs->body);
+        FreePgfText(name);
+        return res;
     } else
     if (PyObject_TypeCheck(pyobj, &pgf_ExprAppType)) {
         ExprAppObject *eapp = (ExprAppObject *)expr;
@@ -429,7 +458,10 @@ match_expr(PgfMarshaller *this, PgfUnmarshaller *u, PgfExpr expr)
     } else
     if (PyObject_TypeCheck(pyobj, &pgf_ExprFunType)) {
         ExprFunObject *efun = (ExprFunObject *)expr;
-        return u->vtbl->efun(u, PyUnicode_AsPgfText(efun->name));
+        PgfText *name = PyUnicode_AsPgfText(efun->name);
+        object res = u->vtbl->efun(u, name);
+        FreePgfText(name);
+        return res;
     } else
     if (PyObject_TypeCheck(pyobj, &pgf_ExprVarType)) {
         ExprVarObject *evar = (ExprVarObject *)expr;
@@ -480,6 +512,7 @@ match_type(PgfMarshaller *this, PgfUnmarshaller *u, PgfType ty)
         free(hypos[i].cid);
         Py_DECREF(hypos[i].type);
     }
+    PyMem_Free(hypos);
     FreePgfText(cat);
 
     return res;
diff --git a/src/runtime/python/pypgf.c b/src/runtime/python/pypgf.c
index 5e27ab7f2..02d9a756a 100644
--- a/src/runtime/python/pypgf.c
+++ b/src/runtime/python/pypgf.c
@@ -150,6 +150,12 @@ PGF_categoryContext(PGFObject *self, PyObject *args)
 
     PyObject *contexts = PyList_FromHypos(hypos, n_hypos);
 
+    for (size_t i = 0; i < n_hypos; i++) {
+        free(hypos[i].cid);
+        Py_DECREF((PyObject *)hypos[i].type);
+    }
+    free(hypos);
+
     return contexts;
 }
 
diff --git a/src/runtime/python/transactions.c b/src/runtime/python/transactions.c
index c2894f550..f2c5d5249 100644
--- a/src/runtime/python/transactions.c
+++ b/src/runtime/python/transactions.c
@@ -29,6 +29,7 @@ PGF_checkoutBranch(PGFObject *self, PyObject *args)
         return NULL;
     }
 
+    pgf_free_revision(self->db, self->revision);
     self->revision = rev;
 
     Py_RETURN_TRUE;
@@ -202,8 +203,14 @@ Transaction_createCategory(TransactionObject *self, PyObject *args)
 
     PgfExn err;
     pgf_create_category(self->pgf->db, self->revision, catname, n_hypos, context, prob, &marshaller, &err);
+
     FreePgfText(catname);
-    if (handleError(err) != PGF_EXN_NONE) {
+    for (Py_ssize_t i = 0; i < n_hypos; i++) {
+        FreePgfText(context[i].cid);
+    }
+    PyMem_Free(context);
+
+    if (handleError(err) != PGF_EXN_NONE) {        
         return NULL;
     }