diff --git a/src/blame.c b/src/blame.c
index 80b8208..b238f05 100644
--- a/src/blame.c
+++ b/src/blame.c
@@ -69,14 +69,20 @@ wrap_blame_hunk(const git_blame_hunk *hunk, Blame *blame)
         py_hunk->lines_in_hunk = hunk->lines_in_hunk;
         py_hunk->final_commit_id = git_oid_allocfmt(&hunk->final_commit_id);
         py_hunk->final_start_line_number = hunk->final_start_line_number;
-        py_hunk->final_signature = hunk->final_signature != NULL ?
-            git_signature_dup(hunk->final_signature) : NULL;
+
+	py_hunk->final_signature = NULL;
+	if (hunk->final_signature)
+		git_signature_dup(&py_hunk->final_signature, hunk->final_signature);
+
         py_hunk->orig_commit_id = git_oid_allocfmt(&hunk->orig_commit_id);
         py_hunk->orig_path = hunk->orig_path != NULL ?
             strdup(hunk->orig_path) : NULL;
         py_hunk->orig_start_line_number = hunk->orig_start_line_number;
-        py_hunk->orig_signature = hunk->orig_signature != NULL ?
-            git_signature_dup(hunk->orig_signature) : NULL;
+
+	py_hunk->orig_signature = NULL;
+	if (hunk->orig_signature)
+		git_signature_dup(&py_hunk->orig_signature, hunk->orig_signature);
+
         py_hunk->boundary = hunk->boundary;
     }
 
diff --git a/src/reference.c b/src/reference.c
index e597e35..1c78d41 100644
--- a/src/reference.c
+++ b/src/reference.c
@@ -62,8 +62,7 @@ RefLogIter_iternext(RefLogIter *self)
         py_entry->oid_old = git_oid_allocfmt(git_reflog_entry_id_old(entry));
         py_entry->oid_new = git_oid_allocfmt(git_reflog_entry_id_new(entry));
         py_entry->message = strdup(git_reflog_entry_message(entry));
-        py_entry->signature = git_signature_dup(
-            git_reflog_entry_committer(entry));
+	git_signature_dup(&py_entry->signature, git_reflog_entry_committer(entry));
 
         ++(self->i);
 
diff --git a/src/tree.c b/src/tree.c
index d1968fa..b72d578 100644
--- a/src/tree.c
+++ b/src/tree.c
@@ -284,20 +284,20 @@ TreeEntry *
 Tree_getitem_by_index(Tree *self, PyObject *py_index)
 {
     int index;
-    const git_tree_entry *entry;
+    const git_tree_entry *entry_src;
+    git_tree_entry *entry;
 
     index = Tree_fix_index(self, py_index);
     if (PyErr_Occurred())
         return NULL;
 
-    entry = git_tree_entry_byindex(self->tree, index);
-    if (!entry) {
+    entry_src = git_tree_entry_byindex(self->tree, index);
+    if (!entry_src) {
         PyErr_SetObject(PyExc_IndexError, py_index);
         return NULL;
     }
 
-    entry = git_tree_entry_dup(entry);
-    if (entry == NULL) {
+    if (git_tree_entry_dup(&entry, entry_src) < 0) {
         PyErr_SetNone(PyExc_MemoryError);
         return NULL;
     }
@@ -550,16 +550,16 @@ TreeIter_dealloc(TreeIter *self)
 TreeEntry *
 TreeIter_iternext(TreeIter *self)
 {
-    const git_tree_entry *entry;
+    const git_tree_entry *entry_src;
+    git_tree_entry *entry;
 
-    entry = git_tree_entry_byindex(self->owner->tree, self->i);
-    if (!entry)
+    entry_src = git_tree_entry_byindex(self->owner->tree, self->i);
+    if (!entry_src)
         return NULL;
 
     self->i += 1;
 
-    entry = git_tree_entry_dup(entry);
-    if (entry == NULL) {
+    if (git_tree_entry_dup(&entry, entry_src) < 0) {
         PyErr_SetNone(PyExc_MemoryError);
         return NULL;
     }
diff --git a/src/treebuilder.c b/src/treebuilder.c
index 8354b1b..5957040 100644
--- a/src/treebuilder.c
+++ b/src/treebuilder.c
@@ -105,19 +105,19 @@ PyObject *
 TreeBuilder_get(TreeBuilder *self, PyObject *py_filename)
 {
     char *filename;
-    const git_tree_entry *entry;
+    const git_tree_entry *entry_src;
+    git_tree_entry *entry;
 
     filename = py_path_to_c_str(py_filename);
     if (filename == NULL)
         return NULL;
 
-    entry = git_treebuilder_get(self->bld, filename);
+    entry_src = git_treebuilder_get(self->bld, filename);
     free(filename);
-    if (entry == NULL)
+    if (entry_src == NULL)
         Py_RETURN_NONE;
 
-    entry = git_tree_entry_dup(entry);
-    if (entry == NULL) {
+    if (git_tree_entry_dup(&entry, entry_src) < 0) {
         PyErr_SetNone(PyExc_MemoryError);
         return NULL;
     }