diff --git a/src/libslic3r/PerimeterGenerator.cpp b/src/libslic3r/PerimeterGenerator.cpp
index 448ac2b90..cf835d160 100644
--- a/src/libslic3r/PerimeterGenerator.cpp
+++ b/src/libslic3r/PerimeterGenerator.cpp
@@ -1715,7 +1715,7 @@ void PerimeterGenerator::_merge_thin_walls(ExtrusionEntityCollection &extrusions
                 searcher.search_result.loop->paths.insert(searcher.search_result.loop->paths.begin() + 1 + searcher.search_result.idx_path,
                     change_flow.paths.begin(), change_flow.paths.end());
                 //add the real extrusion path
-                change_flow.percent_extrusion = 0.9f;
+                change_flow.percent_extrusion = 9.f; // 0.9 but as we modified it by 0.1 just before, has to multiply by 10
                 change_flow.paths = std::vector<ExtrusionPath>();
                 change_flow.use(tws);
                 searcher.search_result.loop->paths.insert(searcher.search_result.loop->paths.begin() + 1 + searcher.search_result.idx_path,