diff --git a/src/libslic3r/Algorithm/RegionExpansion.cpp b/src/libslic3r/Algorithm/RegionExpansion.cpp
index 844cda822..e36f5e62c 100644
--- a/src/libslic3r/Algorithm/RegionExpansion.cpp
+++ b/src/libslic3r/Algorithm/RegionExpansion.cpp
@@ -206,7 +206,7 @@ std::vector<WaveSeed> wave_seeds(
 {
     assert(tiny_expansion > 0);
 
-    if (src.empty())
+    if (src.empty() || boundary.empty())
         return {};
 
     using Intersection  = ClipperZUtils::ClipperZIntersectionVisitor::Intersection;