diff --git a/ext/rugged/rugged.c b/ext/rugged/rugged.c
index 94089f9ff..019459734 100644
--- a/ext/rugged/rugged.c
+++ b/ext/rugged/rugged.c
@@ -43,7 +43,11 @@ static VALUE rb_git_raw_to_hex(VALUE self, VALUE raw)
 	char out[40];
 
 	Check_Type(raw, T_STRING);
-	git_oid_fromraw(&oid, StringValueCStr(raw));
+
+	if (RSTRING_LEN(raw) != GIT_OID_RAWSZ)
+		rb_raise(rb_eTypeError, "Invalid buffer size for an OID");
+
+	git_oid_fromraw(&oid, RSTRING_PTR(raw));
 	git_oid_fmt(out, &oid);
 
 	return rugged_str_new(out, 40, NULL);
diff --git a/test/lib_test.rb b/test/lib_test.rb
index 24089e503..53b4145ba 100644
--- a/test/lib_test.rb
+++ b/test/lib_test.rb
@@ -30,4 +30,11 @@
     hex2 = raw.unpack("H*")[0]
     assert_equal hex1, hex2
   end
+
+  test "converts raw into hex with null bytes" do
+    raw = Rugged::hex_to_raw("702f00394564b24052511cb69961164828bf5494")
+    hex1 = Rugged::raw_to_hex(raw)
+    hex2 = raw.unpack("H*")[0]
+    assert_equal hex1, hex2
+  end
 end