diff --git a/src/libslic3r/PrintConfig.hpp b/src/libslic3r/PrintConfig.hpp
index 792eaf0b3..1f9617a5a 100644
--- a/src/libslic3r/PrintConfig.hpp
+++ b/src/libslic3r/PrintConfig.hpp
@@ -153,8 +153,8 @@ enum BrimType {
     btOuterAndInner,
 };
 
-enum TimelapseType {
-    tlTraditional,
+enum TimelapseType : int {
+    tlTraditional = 0,
     tlSmooth
 };