diff --git a/lib/dsl/grammar.txt b/lib/dsl/grammar.txt
index 57a13593..b3e5fdc6 100644
--- a/lib/dsl/grammar.txt
+++ b/lib/dsl/grammar.txt
@@ -232,7 +232,7 @@ entityList
 
 relationshipType = "OneToOne" {return "one-to-one";} / "OneToMany" {return "one-to-many";} / "ManyToOne" {return "many-to-one";} / "ManyToMany" {return "many-to-many";}
 
-type "a type" = head:[A-Z]tail:[a-zA-Z0-9]* {return makeString(concat([head],tail));} //we must check afterward if the type is acceptable.
+type "a type" = head:[A-Z]tail:[a-zA-Z0-9]* {return head + tail.join('');}
 
 validation 
   = "required" {return {key:'required', value:''};}
@@ -253,22 +253,24 @@ REGEXP "a regular expression"
   = word:[a-zA-Z0-9!@#$%^&*()_+\-=\[\]{};':\\|,.<>\/? ]* {return makeString(word);}
 
 ENUMNAME "an enum name"
-  = head:[A-Z]tail:[a-zA-Z0-9]* {return makeString(concat([head],tail));}
+  = head:[A-Z]tail:[a-zA-Z0-9]* {return head + tail.join('');}
 
 ENUMPROP "an enum property"
-  = underscore:[_]*head:[A-Z0-9]tail:[A-Z0-9_]* {return makeString(concat(concat(underscore,[head]), tail));}
+  = underscore:[_]*head:[A-Z0-9]tail:[A-Z0-9_]* {
+  	return underscore.join('') + head + tail.join('');
+  }
 
 INTEGER "integer"
   = int:[0-9]+ {return parseInt(int.join(""), 10);} 
 
 INJECTEDFIELDNAME "an injected field"
-  = head:[a-zA-Z]tail:[a-zA-Z0-9()]* {return makeString(concat([head],tail));}
+  = head:[a-zA-Z]tail:[a-zA-Z0-9()]* {return head + tail.join('');}
 
 ENTITYNAME "an entity name"  
-  = head:[A-Z]tail:[a-zA-Z0-9]* {return makeString(concat([head],tail));}
+  = head:[A-Z]tail:[a-zA-Z0-9]* {return head + tail.join('');}
 
 FIELDNAME "a field name"
-  = head:[a-zA-Z]tail:[a-zA-Z0-9]* {return makeString(concat([head],tail));}               
+  = head:[a-zA-Z]tail:[a-zA-Z0-9]* {return head + tail.join('');}               
 
 space "a space"
   = space:['\n'|'\t'|'\r'|' '|\u2028|\u2029]+ 
diff --git a/lib/dsl/jdl_parser.js b/lib/dsl/jdl_parser.js
index ddb8adf4..d00c122e 100644
--- a/lib/dsl/jdl_parser.js
+++ b/lib/dsl/jdl_parser.js
@@ -191,7 +191,7 @@ module.exports = (function() {
         peg$c106 = { type: "class", value: "[A-Z]", description: "[A-Z]" },
         peg$c107 = /^[a-zA-Z0-9]/,
         peg$c108 = { type: "class", value: "[a-zA-Z0-9]", description: "[a-zA-Z0-9]" },
-        peg$c109 = function(head, tail) {return makeString(concat([head],tail));},
+        peg$c109 = function(head, tail) {return head + tail.join('');},
         peg$c110 = "required",
         peg$c111 = { type: "literal", value: "required", description: "\"required\"" },
         peg$c112 = function() {return {key:'required', value:''};},
@@ -229,7 +229,9 @@ module.exports = (function() {
         peg$c144 = { type: "class", value: "[A-Z0-9]", description: "[A-Z0-9]" },
         peg$c145 = /^[A-Z0-9_]/,
         peg$c146 = { type: "class", value: "[A-Z0-9_]", description: "[A-Z0-9_]" },
-        peg$c147 = function(underscore, head, tail) {return makeString(concat(concat(underscore,[head]), tail));},
+        peg$c147 = function(underscore, head, tail) {
+          return underscore.join('') + head + tail.join('');
+        },
         peg$c148 = { type: "other", description: "integer" },
         peg$c149 = /^[0-9]/,
         peg$c150 = { type: "class", value: "[0-9]", description: "[0-9]" },