diff --git a/src/Geometry.cpp b/src/Geometry.cpp
index 9df30869..39d8395c 100644
--- a/src/Geometry.cpp
+++ b/src/Geometry.cpp
@@ -161,6 +161,12 @@ Geometry::Geometry( Geometry const& other ) : validityFlag_( other.validityFlag_
 
 }
 
+Geometry& Geometry::operator=( const Geometry& other )
+{
+    validityFlag_ = other.validityFlag_;
+    return *this;
+}
+
 bool Geometry::hasValidityFlag() const
 {
         return validityFlag_;
diff --git a/src/Geometry.h b/src/Geometry.h
index 8241bb2b..016c5d19 100644
--- a/src/Geometry.h
+++ b/src/Geometry.h
@@ -282,7 +282,7 @@ class SFCGAL_API Geometry {
 protected:
     Geometry();
     Geometry( const Geometry& );
-    const Geometry& operator=( const Geometry& );
+    Geometry& operator=( const Geometry& other );
 
     bool validityFlag_;
 };