diff --git a/NSspi/Contexts/SafeContextHandle.cs b/NSspi/Contexts/SafeContextHandle.cs
index 393056e..7fbddf7 100644
--- a/NSspi/Contexts/SafeContextHandle.cs
+++ b/NSspi/Contexts/SafeContextHandle.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.ConstrainedExecution;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -13,6 +14,7 @@ namespace NSspi.Contexts
             : base()
         { }
 
+        [ReliabilityContract( Consistency.WillNotCorruptState, Cer.Success )]
         protected override bool ReleaseHandle()
         {
             SecurityStatus status = ContextNativeMethods.DeleteSecurityContext(
diff --git a/NSspi/Credentials/SafeCredentialHandle.cs b/NSspi/Credentials/SafeCredentialHandle.cs
index e6dfa93..2f6eaff 100644
--- a/NSspi/Credentials/SafeCredentialHandle.cs
+++ b/NSspi/Credentials/SafeCredentialHandle.cs
@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.ConstrainedExecution;
 using System.Text;
 using System.Threading.Tasks;
 
@@ -13,6 +14,7 @@ namespace NSspi.Credentials
             : base()
         { }
 
+        [ReliabilityContract( Consistency.WillNotCorruptState, Cer.Success )]
         protected override bool ReleaseHandle()
         {
             SecurityStatus status = CredentialNativeMethods.FreeCredentialsHandle(