diff --git a/tle.hh b/tle.hh
index 83e8f5d..4765e66 100644
--- a/tle.hh
+++ b/tle.hh
@@ -2,6 +2,7 @@
 #include <string>
 #include <map>
 #include <memory>
+#include <ctime>
 class SGP4;
 class Tle;