diff --git a/src/libslic3r/GCode/ThumbnailData.hpp b/src/libslic3r/GCode/ThumbnailData.hpp
index 1a41c7486e..82563d64f2 100644
--- a/src/libslic3r/GCode/ThumbnailData.hpp
+++ b/src/libslic3r/GCode/ThumbnailData.hpp
@@ -32,7 +32,7 @@ using ThumbnailsList = std::vector<ThumbnailData>;
 
 struct ThumbnailsParams
 {
-	const Vec2ds 	sizes;
+	const Vec2ds 	sizes{};
 	bool 			printable_only;
 	bool 			parts_only;
 	bool 			show_bed;