@@ -146,11 +146,11 @@
             throw RangeError("# Error. Unknown dictionary compression method: " + this.nCompressionMethod);
         }
         // <dChar> to get the value of an arc, <dCharVal> to get the char of an arc with its value
         this.dChar = helpers.objectToMap(this.dChar);
         this.dCharVal = this.dChar.gl_reverse();
-        this.a2grams = new Set(this.l2grams);
+        this.a2grams = (this.l2grams) ? new Set(this.l2grams) : null;
 
         if (this.cStemming == "S") {
             this.funcStemming = str_transform.changeWordWithSuffixCode;
         } else if (this.cStemming == "A") {
             this.funcStemming = str_transform.changeWordWithAffixCode;
@@ -412,10 +412,13 @@
     }
 
     isNgramsOK (sChars) {
         if (sChars.length != 2) {
             return true;
+        }
+        if (!this.a2grams) {
+            return true;
         }
         return this.a2grams.has(sChars);
     }
 
     * _getCharArcs (iAddr) {