diff --git a/library/entropy_poll.c b/library/entropy_poll.c
index 25a27be..01bd58e 100644
--- a/library/entropy_poll.c
+++ b/library/entropy_poll.c
@@ -61,7 +61,10 @@
     }
 
     if( CryptGenRandom( provider, (DWORD) len, output ) == FALSE )
+    {
+        CryptReleaseContext( provider, 0 );
         return( MBEDTLS_ERR_ENTROPY_SOURCE_FAILED );
+    }
 
     CryptReleaseContext( provider, 0 );
     *olen = len;