diff --git a/FDTD/operator_sse.cpp b/FDTD/operator_sse.cpp
index 8a1b21b..214bf3a 100644
--- a/FDTD/operator_sse.cpp
+++ b/FDTD/operator_sse.cpp
@@ -41,11 +41,11 @@ Operator_sse::~Operator_sse()
 	Delete();
 }
 
-Engine* Operator_sse::CreateEngine() const
+Engine* Operator_sse::CreateEngine()
 {
 	//! create a special sse-engine
-	Engine_sse* eng = Engine_sse::New(this);
-	return eng;
+	m_Engine = Engine_sse::New(this);
+	return m_Engine;
 }
 
 void Operator_sse::Init()
diff --git a/FDTD/operator_sse.h b/FDTD/operator_sse.h
index 317ea72..c0a698a 100644
--- a/FDTD/operator_sse.h
+++ b/FDTD/operator_sse.h
@@ -29,7 +29,7 @@ public:
 	static Operator_sse* New();
 	virtual ~Operator_sse();
 
-	virtual Engine* CreateEngine() const;
+	virtual Engine* CreateEngine();
 
 	inline virtual FDTD_FLOAT GetVV( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) const { return f4_vv[n][x][y][z%numVectors].f[z/numVectors]; }
 	inline virtual FDTD_FLOAT GetVI( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) const { return f4_vi[n][x][y][z%numVectors].f[z/numVectors]; }
diff --git a/FDTD/operator_sse_compressed.cpp b/FDTD/operator_sse_compressed.cpp
index 5214892..ce3e8e3 100644
--- a/FDTD/operator_sse_compressed.cpp
+++ b/FDTD/operator_sse_compressed.cpp
@@ -42,16 +42,14 @@ Operator_SSE_Compressed::~Operator_SSE_Compressed()
 	Delete();
 }
 
-Engine* Operator_SSE_Compressed::CreateEngine() const
+Engine* Operator_SSE_Compressed::CreateEngine()
 {
 	if (!m_Use_Compression)
-	{
 		//! create a default sse-engine
-		Engine_sse* eng = Engine_sse::New(this);
-		return eng;
-	}
-	Engine_SSE_Compressed* eng = Engine_SSE_Compressed::New(this);
-	return eng;
+		m_Engine = Engine_sse::New(this);
+  else
+	  m_Engine = Engine_SSE_Compressed::New(this);
+	return m_Engine;
 }
 
 int Operator_SSE_Compressed::CalcECOperator( DebugFlags debugFlags )
diff --git a/FDTD/operator_sse_compressed.h b/FDTD/operator_sse_compressed.h
index 5d3454f..f9b12a2 100644
--- a/FDTD/operator_sse_compressed.h
+++ b/FDTD/operator_sse_compressed.h
@@ -43,7 +43,7 @@ public:
 	static Operator_SSE_Compressed* New();
 	virtual ~Operator_SSE_Compressed();
 
-	virtual Engine* CreateEngine() const;
+	virtual Engine* CreateEngine();
 
 	inline virtual FDTD_FLOAT GetVV( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) const { if (m_Use_Compression) return f4_vv_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetVV(n,x,y,z);}
 	inline virtual FDTD_FLOAT GetVI( unsigned int n, unsigned int x, unsigned int y, unsigned int z ) const { if (m_Use_Compression) return f4_vi_Compressed[n][m_Op_index[x][y][z%numVectors]].f[z/numVectors]; else return Operator_sse::GetVI(n,x,y,z);}