diff --git a/src/libslic3r/Layer.cpp b/src/libslic3r/Layer.cpp
index ddf68c46ba..d60e077af0 100644
--- a/src/libslic3r/Layer.cpp
+++ b/src/libslic3r/Layer.cpp
@@ -167,7 +167,7 @@ static void connect_layer_slices(
                                 // Second source contour of this expolygon was found.
                                 if (i > j)
                                     std::swap(i, j);
-                                assert_intersection_valid(i, j);
+                                assert(assert_intersection_valid(i, j));
                                 goto end;
                             }
                         }