diff --git a/lib/control.js b/lib/control.js
index a7c2688..778b847 100644
--- a/lib/control.js
+++ b/lib/control.js
@@ -63,8 +63,10 @@ Control.prototype.parse = function(ber) {
 
   if (ber.length) {
     this.type = ber.readString();
-    if (ber.offset < end)
-      this.criticality = ber.readBoolean();
+    if (ber.offset < end) {
+      if (ber.peek() === 0x01) // Boolean, optional
+        this.criticality = ber.readBoolean();
+    }
 
     if (ber.offset < end)
       this.value = ber.readString();