diff --git a/include/core/processor/processor_base.h b/include/core/processor/processor_base.h
index b88d6714f0c7ea715b64f4799fde91dedefd5224..a5813256ca0e195512c370988cff7ce6c2359429 100644
--- a/include/core/processor/processor_base.h
+++ b/include/core/processor/processor_base.h
@@ -96,14 +96,14 @@ public:
     * Check if the time distance between two time stamps is smaller than
     * the time tolerance.
     */
-    bool simpleCheckTimeTolerance(const TimeStamp& _time_stamp1, const TimeStamp& _time_stamp2, const Scalar& _time_tolerance);
+    static bool simpleCheckTimeTolerance(const TimeStamp& _time_stamp1, const TimeStamp& _time_stamp2, const Scalar& _time_tolerance);
 
     /**\brief Check time tolerance
     *
     * Check if the time distance between two time stamps is smaller than
     * the minimum time tolerance of the two frames.
     */
-    bool doubleCheckTimeTolerance(const TimeStamp& _time_stamp1, const Scalar& _time_tolerance1, const TimeStamp& _time_stamp2, const Scalar& _time_tolerance2);
+    static bool doubleCheckTimeTolerance(const TimeStamp& _time_stamp1, const Scalar& _time_tolerance1, const TimeStamp& _time_stamp2, const Scalar& _time_tolerance2);
 
 protected:
 
@@ -143,7 +143,7 @@ class BufferPackKeyFrame : public Buffer<PackKeyFramePtr>
         /**\brief Alias funct
         *
         */
-        bool checkTimeTolerance(const TimeStamp& _time_stamp1, const Scalar& _time_tolerance1, const TimeStamp& _time_stamp2, const Scalar& _time_tolerance2)
+        static bool checkTimeTolerance(const TimeStamp& _time_stamp1, const Scalar& _time_tolerance1, const TimeStamp& _time_stamp2, const Scalar& _time_tolerance2)
         { return doubleCheckTimeTolerance(_time_stamp1, _time_tolerance1, _time_stamp2, _time_tolerance2); };
 
 };