diff --git a/src/datetime.c b/src/datetime.c
index 619051c..b6c3576 100644
--- a/src/datetime.c
+++ b/src/datetime.c
@@ -110,3 +110,21 @@ dc_datetime_gmtime (dc_datetime_t *result,
 
 	return result;
 }
+
+dc_ticks_t
+dc_datetime_mktime (dc_datetime_t *dt)
+{
+	if (dt == NULL)
+		return -1;
+
+	struct tm tm;
+	tm.tm_year = dt->year - 1900;
+	tm.tm_mon = dt->month - 1;
+	tm.tm_mday = dt->day;
+	tm.tm_hour = dt->hour;
+	tm.tm_min = dt->minute;
+	tm.tm_sec = dt->second;
+	tm.tm_isdst = -1;
+
+	return mktime (&tm);
+}
diff --git a/src/datetime.h b/src/datetime.h
index ebd191e..748a736 100644
--- a/src/datetime.h
+++ b/src/datetime.h
@@ -52,6 +52,9 @@ dc_datetime_t *
 dc_datetime_gmtime (dc_datetime_t *result,
                     dc_ticks_t ticks);
 
+dc_ticks_t
+dc_datetime_mktime (dc_datetime_t *dt);
+
 #ifdef __cplusplus
 }
 #endif /* __cplusplus */
diff --git a/src/libdivecomputer.symbols b/src/libdivecomputer.symbols
index d534cc0..7ff4532 100644
--- a/src/libdivecomputer.symbols
+++ b/src/libdivecomputer.symbols
@@ -15,6 +15,7 @@ dc_buffer_get_data
 dc_datetime_now
 dc_datetime_localtime
 dc_datetime_gmtime
+dc_datetime_mktime
 
 parser_get_type
 parser_set_data