diff --git a/GstToolkit.cpp b/GstToolkit.cpp
index 13222ba..c676f9b 100644
--- a/GstToolkit.cpp
+++ b/GstToolkit.cpp
@@ -32,7 +32,7 @@ string GstToolkit::date_time_string()
     return oss.str();
 }
 
-string GstToolkit::time_to_string(guint64 t)
+string GstToolkit::time_to_string(ulong t)
 {
     if (t == GST_CLOCK_TIME_NONE)
         return "00:00:00.00";
diff --git a/GstToolkit.h b/GstToolkit.h
index fa48509..9beea14 100644
--- a/GstToolkit.h
+++ b/GstToolkit.h
@@ -4,12 +4,11 @@
 #include <string>
 #include <list>
 
-
 namespace GstToolkit
 {
 
     std::string date_time_string();
-    std::string time_to_string(guint64 t);
+    std::string time_to_string(ulong t);
 
     std::string gst_version();
     std::list<std::string> all_plugins();