diff --git a/dlls/secur32/schannel.c b/dlls/secur32/schannel.c
index 1f4a1005550..289802c5b32 100644
--- a/dlls/secur32/schannel.c
+++ b/dlls/secur32/schannel.c
@@ -1299,7 +1299,8 @@ static SECURITY_STATUS SEC_ENTRY schan_EncryptMessage(PCtxtHandle context_handle
     SIZE_T data_size;
     SIZE_T length;
     char *data;
-    int idx;
+    int idx, output_buffer_idx = -1;
+    ULONG output_offset = 0;
 
     TRACE("context_handle %p, quality %ld, message %p, message_seq_no %ld\n",
             context_handle, quality, message, message_seq_no);
@@ -1326,8 +1327,13 @@ static SECURITY_STATUS SEC_ENTRY schan_EncryptMessage(PCtxtHandle context_handle
     params.output = message;
     params.buffer = data;
     params.length = &length;
+    params.output_buffer_idx = &output_buffer_idx;
+    params.output_offset = &output_offset;
     status = GNUTLS_CALL( send, &params );
 
+    if (!status && output_buffer_idx != -1)
+        message->pBuffers[output_buffer_idx].cbBuffer = output_offset;
+
     TRACE("Sent %Id bytes.\n", length);
 
     if (length != data_size)
diff --git a/dlls/secur32/schannel_gnutls.c b/dlls/secur32/schannel_gnutls.c
index 82437207982..ebce6bacde0 100644
--- a/dlls/secur32/schannel_gnutls.c
+++ b/dlls/secur32/schannel_gnutls.c
@@ -878,7 +878,8 @@ static NTSTATUS schan_send( void *args )
         }
     }
 
-    t->out.desc->pBuffers[t->out.current_buffer_idx].cbBuffer = t->out.offset;
+    *params->output_buffer_idx = t->out.current_buffer_idx;
+    *params->output_offset = t->out.offset;
     return SEC_E_OK;
 }
 
diff --git a/dlls/secur32/secur32_priv.h b/dlls/secur32/secur32_priv.h
index 574d3d51cb5..8a494309710 100644
--- a/dlls/secur32/secur32_priv.h
+++ b/dlls/secur32/secur32_priv.h
@@ -167,6 +167,8 @@ struct send_params
     SecBufferDesc *output;
     const void *buffer;
     SIZE_T *length;
+    int *output_buffer_idx;
+    ULONG *output_offset;
 };
 
 struct set_application_protocols_params