diff --git a/git.go b/git.go
index b20f993..f69ecc8 100644
--- a/git.go
+++ b/git.go
@@ -3,7 +3,7 @@
 /*
 #cgo pkg-config: libgit2
 #include <git2.h>
-#include <git2/errors.h>
+#include <string.h>
 */
 import "C"
 import (
@@ -38,7 +38,8 @@
 	}
 
 	oid := new(Oid)
-	copy(oid[0:20], C.GoBytes(unsafe.Pointer(coid), 20))
+
+	C.memcpy(unsafe.Pointer(oid), unsafe.Pointer(coid), 20)
 	return oid
 }