diff --git a/include/mtime_datetime.h b/include/mtime_datetime.h
index be10d886c210bb58f8470e38b42c077b2a4918b1..37dff6e0c47e7d89ecd3afbf0a19ddad2a21fbcb 100644
--- a/include/mtime_datetime.h
+++ b/include/mtime_datetime.h
@@ -71,8 +71,13 @@ int
 getNoOfDaysInYearDateTime(struct _datetime* dt);
 
 /*! \cond PRIVATE */
-bool
-testYearIsLeapYear(int64_t year);
+static inline bool
+testYearIsLeapYear(int64_t year)
+{
+  bool isLeapYear = !(year % 400) || ((year % 100) && !(year % 4));
+  return isLeapYear;
+}
+
 
 struct _datetime *
 convertDateToDateTime(struct _date* d, struct _datetime* dt_return);
diff --git a/src/mtime_datetime.c b/src/mtime_datetime.c
index cc71bc0921ecf5b8a4a44a31a0db9765bc4d2d3a..1fc55971386efe9153ec22054b689dedbc0af750 100644
--- a/src/mtime_datetime.c
+++ b/src/mtime_datetime.c
@@ -336,26 +336,6 @@ else
 }
 
 
-/*! \cond PRIVATE */
-/* Internal function. Test is year a leap year? */
-
-bool
-testYearIsLeapYear(int64_t year)
-{
-  bool flag = false;
-
-  if (!(year % 400))
-    flag = true;
-  else if (!(year % 100))
-    flag = false;
-  else if (!(year % 4))
-    flag = true;
-  else
-    flag = false;
-
-  return flag;
-}
-
 /*
  * NOTE: Internal and not doxyfied.
  *