diff --git a/Contexts/Context.cs b/Contexts/Context.cs
index 0822580..5d2a0ca 100644
--- a/Contexts/Context.cs
+++ b/Contexts/Context.cs
@@ -279,13 +279,37 @@ namespace NSspi.Contexts
 
             using ( adapter = new SecureBufferAdapter( new[] { dataBuffer, signatureBuffer } ) )
             {
-                // TODO CER
-                status = ContextNativeMethods.MakeSignature(
-                    ref this.ContextHandle.rawHandle,
-                    0,
-                    adapter.Handle,
-                    0
-                );
+                bool gotRef = false;
+                
+                RuntimeHelpers.PrepareConstrainedRegions();
+                try
+                {
+                    this.ContextHandle.DangerousAddRef( ref gotRef );
+                }
+                catch ( Exception )
+                {
+                    if ( gotRef )
+                    {
+                        this.ContextHandle.DangerousRelease();
+                        gotRef = false;
+                    }
+
+                    throw;
+                }
+                finally
+                {
+                    if ( gotRef )
+                    {
+                        status = ContextNativeMethods.MakeSignature(
+                            ref this.ContextHandle.rawHandle,
+                            0,
+                            adapter.Handle,
+                            0
+                        );
+
+                        this.ContextHandle.DangerousRelease();
+                    }
+                }
             }
 
             if ( status != SecurityStatus.OK )
@@ -360,12 +384,37 @@ namespace NSspi.Contexts
 
             using ( adapter = new SecureBufferAdapter( new[] { dataBuffer, signatureBuffer } ) )
             {
-                status = ContextNativeMethods.VerifySignature(
-                    ref this.ContextHandle.rawHandle,
-                    adapter.Handle,
-                    0,
-                    0
-                );
+                bool gotRef = false;
+
+                RuntimeHelpers.PrepareConstrainedRegions();
+                try
+                {
+                    this.ContextHandle.DangerousAddRef( ref gotRef );
+                }
+                catch ( Exception )
+                {
+                    if ( gotRef )
+                    {
+                        this.ContextHandle.DangerousRelease();
+                        gotRef = false;
+                    }
+
+                    throw;
+                }
+                finally
+                {
+                    if ( gotRef )
+                    {
+                        status = ContextNativeMethods.VerifySignature(
+                            ref this.ContextHandle.rawHandle,
+                            adapter.Handle,
+                            0,
+                            0
+                        );
+
+                        this.ContextHandle.DangerousRelease();
+                    }
+                }
             }
 
             if ( status == SecurityStatus.OK )