diff --git a/lib/main.js b/lib/main.js
index <HASH>..<HASH> 100644
--- a/lib/main.js
+++ b/lib/main.js
@@ -222,7 +222,7 @@ function sendAction(cmd, type, msg, options) {
         })
         .buffer("dataPacketType", 1)
         .tap(function (vars) {
-            var responseType = parseUtil.int8(vars.dataPacketType);
+            var responseType = parseUtil.int8(vars.dataPacketType) & 0x0F;
 
             if (responseType !== 10) {
                 errorString = "Invalid response (expecting SEXP)";
Mask response type with 0x0F.

See #<I>.