diff --git a/src/Mod/Part/App/Geometry.cpp b/src/Mod/Part/App/Geometry.cpp
index ed4604b29f..c9ce273258 100644
--- a/src/Mod/Part/App/Geometry.cpp
+++ b/src/Mod/Part/App/Geometry.cpp
@@ -288,7 +288,7 @@ bool Geometry::hasExtension(std::string name) const
     return false;
 }
 
-std::weak_ptr<const GeometryExtension> Geometry::getExtension(Base::Type type) const
+std::weak_ptr<GeometryExtension> Geometry::getExtension(Base::Type type)
 {
     for( auto ext : extensions) {
         if(ext->getTypeId() == type)
@@ -298,7 +298,7 @@ std::weak_ptr<const GeometryExtension> Geometry::getExtension(Base::Type type) c
     throw Base::ValueError("No geometry extension of the requested type.");
 }
 
-std::weak_ptr<const GeometryExtension> Geometry::getExtension(std::string name) const
+std::weak_ptr<GeometryExtension> Geometry::getExtension(std::string name)
 {
     for( auto ext : extensions) {
         if(ext->getName() == name)
@@ -308,6 +308,17 @@ std::weak_ptr<const GeometryExtension> Geometry::getExtension(std::string name)
     throw Base::ValueError("No geometry extension with the requested name.");
 }
 
+std::weak_ptr<const GeometryExtension> Geometry::getExtension(Base::Type type) const
+{
+    return const_cast<Geometry*>(this)->getExtension(type).lock();
+}
+
+std::weak_ptr<const GeometryExtension> Geometry::getExtension(std::string name) const
+{
+    return const_cast<Geometry*>(this)->getExtension(name).lock();
+}
+
+
 void Geometry::setExtension(std::unique_ptr<GeometryExtension> && geo)
 {
     bool hasext=false;
diff --git a/src/Mod/Part/App/Geometry.h b/src/Mod/Part/App/Geometry.h
index 9ed35a73a2..f05f554cf9 100644
--- a/src/Mod/Part/App/Geometry.h
+++ b/src/Mod/Part/App/Geometry.h
@@ -107,6 +107,8 @@ public:
     bool hasExtension(std::string name) const;
     std::weak_ptr<const GeometryExtension> getExtension(Base::Type type) const;
     std::weak_ptr<const GeometryExtension> getExtension(std::string name) const;
+    std::weak_ptr<GeometryExtension> getExtension(Base::Type type);
+    std::weak_ptr<GeometryExtension> getExtension(std::string name);
     void setExtension(std::unique_ptr<GeometryExtension> &&geo);
     void deleteExtension(Base::Type type);
     void deleteExtension(std::string name);