diff --git a/blob.go b/blob.go
index 91064b1..f7db15e 100644
--- a/blob.go
+++ b/blob.go
@@ -7,6 +7,7 @@ package git
 */
 import "C"
 import (
+	"runtime"
 	"unsafe"
 )
 
@@ -14,8 +15,9 @@ type Blob struct {
 	ptr *C.git_object
 }
 
-func freeBlob(blob *Blob) {
-	C.git_object_free(blob.ptr)
+func (v *Blob) Free() {
+	runtime.SetFinalizer(v, nil)
+	C.git_object_free(v.ptr)
 }
 
 func (v *Blob) Contents() []byte {
diff --git a/commit.go b/commit.go
index 855ed87..779ebd7 100644
--- a/commit.go
+++ b/commit.go
@@ -9,6 +9,7 @@ extern int _go_git_treewalk(git_tree *tree, git_treewalk_mode mode, void *ptr);
 import "C"
 
 import (
+	"runtime"
 	"time"
 )
 
@@ -32,6 +33,8 @@ func (c *Commit) Tree() (*Tree, error) {
 	if err < 0 {
 		return nil, LastError()
 	}
+
+	runtime.SetFinalizer(tree, (*Tree).Free)
 	return tree, nil
 }
 
diff --git a/odb.go b/odb.go
index 5688080..6370999 100644
--- a/odb.go
+++ b/odb.go
@@ -49,7 +49,7 @@ func (v *Odb) Read(oid *Oid) (obj *OdbObject, err error) {
 		return nil, LastError()
 	}
 
-	runtime.SetFinalizer(obj, freeOdbObject)
+	runtime.SetFinalizer(obj, (*OdbObject).Free)
 	return
 }
 
@@ -57,8 +57,9 @@ type OdbObject struct {
 	ptr *C.git_odb_object
 }
 
-func freeOdbObject(obj *OdbObject) {
-	C.git_odb_object_free(obj.ptr)
+func (v *OdbObject) Free() {
+	runtime.SetFinalizer(v, nil)
+	C.git_odb_object_free(v.ptr)
 }
 
 func (v *OdbObject) Type() int {
diff --git a/repository.go b/repository.go
index 755926e..bfbfebd 100644
--- a/repository.go
+++ b/repository.go
@@ -27,7 +27,7 @@ func Open(path string) (*Repository, error) {
 		return nil, LastError()
 	}
 
-	runtime.SetFinalizer(repo, freeRepository)
+	runtime.SetFinalizer(repo, (*Repository).Free)
 	return repo, nil
 }
 
@@ -42,12 +42,13 @@ func Init(path string, isbare bool) (*Repository, error) {
 		return nil, LastError()
 	}
 
-	runtime.SetFinalizer(repo, freeRepository)
+	runtime.SetFinalizer(repo, (*Repository).Free)
 	return repo, nil
 }
 
-func freeRepository(repo *Repository) {
-	C.git_repository_free(repo.ptr)
+func (v *Repository) Free() {
+	runtime.SetFinalizer(v, nil)
+	C.git_repository_free(v.ptr)
 }
 
 func (v *Repository) Config() (*Config, error) {
@@ -127,8 +128,9 @@ func (v *Repository) Commit(
 }
 */
 
-func freeOdb(odb *Odb) {
-	C.git_odb_free(odb.ptr)
+func (v *Odb) Free() {
+	runtime.SetFinalizer(v, nil)
+	C.git_odb_free(v.ptr)
 }
 
 func (v *Repository) Odb() (odb *Odb, err error) {
@@ -137,7 +139,7 @@ func (v *Repository) Odb() (odb *Odb, err error) {
 		return nil, LastError()
 	}
 
-	runtime.SetFinalizer(odb, freeOdb)
+	runtime.SetFinalizer(odb, (*Odb).Free)
 	return
 }
 
diff --git a/tree.go b/tree.go
index 324fc1f..6f1f2d0 100644
--- a/tree.go
+++ b/tree.go
@@ -9,6 +9,7 @@ extern int _go_git_treewalk(git_tree *tree, git_treewalk_mode mode, void *ptr);
 import "C"
 
 import (
+	"runtime"
 	"unsafe"
 )
 
@@ -31,6 +32,7 @@ func newTreeEntry(entry *C.git_tree_entry) *TreeEntry {
 }
 
 func (t *Tree) Free() {
+	runtime.SetFinalizer(t, nil)
 	C.git_tree_free(t.ptr)
 }
 
@@ -40,6 +42,8 @@ func TreeLookup(repo *Repository, oid *Oid) (*Tree, error) {
 	if err < 0 {
 		return nil, LastError()
 	}
+
+	runtime.SetFinalizer(tree, (*Tree).Free)
 	return tree, nil
 }
 
@@ -99,7 +103,8 @@ type TreeBuilder struct {
 	repo *Repository
 }
 
-func freeTreeBuilder(v *TreeBuilder) {
+func (v *TreeBuilder) Free() {
+	runtime.SetFinalizer(v, nil)
 	C.git_treebuilder_free(v.ptr)
 }