diff --git a/source/ContractConfigurator/ExpressionParser/ExpressionParser.cs b/source/ContractConfigurator/ExpressionParser/ExpressionParser.cs
index 7bf252f6..f49dc8eb 100644
--- a/source/ContractConfigurator/ExpressionParser/ExpressionParser.cs
+++ b/source/ContractConfigurator/ExpressionParser/ExpressionParser.cs
@@ -1353,7 +1353,7 @@ public virtual T ParseDataStoreIdentifier(Token token)
 
         public Token ParseIdentifier()
         {
-            Match m = Regex.Match(expression, @"([A-Za-z][\w\d]*).*");
+            Match m = Regex.Match(expression, @"([A-Za-z][A-Za-z0-9_]*).*");
             string identifier = m.Groups[1].Value;
             expression = (expression.Length > identifier.Length ? expression.Substring(identifier.Length) : "");
 
@@ -1365,7 +1365,7 @@ public Token ParseIdentifier()
 
         public Token ParseSpecialIdentifier()
         {
-            Match m = Regex.Match(expression, @"^@(/?(?>([A-Za-z][\w\d]*|\.\.)/)*[A-Za-z][\w\d:]*).*");
+            Match m = Regex.Match(expression, @"^@(/?(?>(?:[A-Za-z][A-Za-z0-9_]*|\.\.)/)*[A-Za-z][A-Za-z0-9_]*(?::[A-Za-z][A-Za-z0-9_]*)*).*");
             string identifier = m.Groups[1].Value;
             expression = (expression.Length > identifier.Length + 1 ? expression.Substring(identifier.Length + 1) : "");
 
@@ -1374,7 +1374,7 @@ public Token ParseSpecialIdentifier()
 
         public Token ParseDataStoreIdentifier()
         {
-            Match m = Regex.Match(expression, @"^\$(/?(?>([A-Za-z][\w\d]*|\.\.)/)*[A-Za-z][\w\d:]*).*");
+            Match m = Regex.Match(expression, @"^\$(/?(?>(?:[A-Za-z][A-Za-z0-9_]*|\.\.)/)*[A-Za-z][A-Za-z0-9_]*(?::[A-Za-z][A-Za-z0-9_]*)*).*");
             string identifier = m.Groups[1].Value;
             expression = (expression.Length > identifier.Length + 1 ? expression.Substring(identifier.Length + 1) : "");
 
diff --git a/source/ContractConfigurator/ExpressionParser/Parsers/SimpleTypes/ListExpressionParser.cs b/source/ContractConfigurator/ExpressionParser/Parsers/SimpleTypes/ListExpressionParser.cs
index 8a5d5d37..3a4cc0c3 100644
--- a/source/ContractConfigurator/ExpressionParser/Parsers/SimpleTypes/ListExpressionParser.cs
+++ b/source/ContractConfigurator/ExpressionParser/Parsers/SimpleTypes/ListExpressionParser.cs
@@ -230,7 +230,7 @@ public TResult ParseWhereMethod<TResult>(List<T> obj)
                 ParseToken("(");
 
                 // Get the identifier for the object
-                Match m = Regex.Match(expression, @"([A-Za-z][\w\d]*)[\s]*=>[\s]*(.*)");
+                Match m = Regex.Match(expression, @"([A-Za-z][A-Za-z0-9_]*)[\s]*=>[\s]*(.*)");
                 string identifier = m.Groups[1].Value;
                 expression = (string.IsNullOrEmpty(identifier) ? expression : m.Groups[2].Value);
 
diff --git a/source/ContractConfigurator/ExpressionParser/Parsers/SimpleTypes/StringExpressionParser.cs b/source/ContractConfigurator/ExpressionParser/Parsers/SimpleTypes/StringExpressionParser.cs
index e9b107aa..cdefcf8c 100644
--- a/source/ContractConfigurator/ExpressionParser/Parsers/SimpleTypes/StringExpressionParser.cs
+++ b/source/ContractConfigurator/ExpressionParser/Parsers/SimpleTypes/StringExpressionParser.cs
@@ -93,7 +93,7 @@ public override TResult ParseStatement<TResult>()
                 else
                 {
                     // Check for an immediate function call 
-                    Match m = Regex.Match(expression, @"^\w[\w\d]*\(");
+                    Match m = Regex.Match(expression, @"^[A-Za-z][A-Za-z0-9_]*\(");
                     if (m.Success)
                     {
                         return base.ParseStatement<TResult>();
@@ -110,7 +110,7 @@ public override TResult ParseStatement<TResult>()
                     int dataStoreIdentifierIndex = m.Success ? m.Index : -1;
 
                     // Look for function calls
-                    m = Regex.Match(expression, @"(\A|\s)\w[\w\d]*\(");
+                    m = Regex.Match(expression, @"(\A|\s)[A-Za-z][A-Za-z0-9_]*\(");
                     int functionIndex = m == Match.Empty ? -1 : m.Index;
 
                     // Look for an end quote