diff --git a/src/libslic3r/SLA/SLAAutoSupports.cpp b/src/libslic3r/SLA/SLAAutoSupports.cpp
index 1f6dcc2b7..aca84dbd8 100644
--- a/src/libslic3r/SLA/SLAAutoSupports.cpp
+++ b/src/libslic3r/SLA/SLAAutoSupports.cpp
@@ -499,6 +499,18 @@ void SLAAutoSupports::uniformly_cover(const ExPolygons& islands, Structure& stru
     }
 }
 
+float SLAAutoSupports::Structure::overlap_area(const Structure &rhs) const
+{
+    double out = 0.;
+    if (this->bbox.overlap(rhs.bbox)) {
+         Polygons polys = intersection(to_polygons(*this->polygon), to_polygons(*rhs.polygon), false);
+         for (const Polygon &poly : polys)
+            out += poly.area();
+    }
+
+    return float(out);
+}
+
 #ifdef SLA_AUTOSUPPORTS_DEBUG
 void SLAAutoSupports::output_structures(const std::vector<Structure>& structures)
 {
diff --git a/src/libslic3r/SLA/SLAAutoSupports.hpp b/src/libslic3r/SLA/SLAAutoSupports.hpp
index b552d1c0b..27f595a74 100644
--- a/src/libslic3r/SLA/SLAAutoSupports.hpp
+++ b/src/libslic3r/SLA/SLAAutoSupports.hpp
@@ -71,15 +71,7 @@ public:
         bool overlaps(const Structure &rhs) const { 
             return this->bbox.overlap(rhs.bbox) && (this->polygon->overlaps(*rhs.polygon) || rhs.polygon->overlaps(*this->polygon)); 
         }
-        float overlap_area(const Structure &rhs) const { 
-            double out = 0.;
-            if (this->bbox.overlap(rhs.bbox)) {
-                 Polygons polys = intersection(to_polygons(*this->polygon), to_polygons(*rhs.polygon), false);
-                 for (const Polygon &poly : polys)
-                    out += poly.area();
-            }
-            return float(out);
-        }
+        float overlap_area(const Structure &rhs) const;
         float area_below() const { 
             float area = 0.f; 
             for (const Link &below : this->islands_below)