diff --git a/Package.resolved b/Package.resolved
index c277d2e..00d1d75 100644
--- a/Package.resolved
+++ b/Package.resolved
@@ -1,5 +1,5 @@
 {
-  "originHash" : "ce25c9bdeb39120a6e58c3aa2fa205e436aca11542cc194f7b4520aecb86b27d",
+  "originHash" : "db12584d48eea6de43652535e6f196bf16b860f1a22c890a09e0ccf979302a90",
   "pins" : [
     {
       "identity" : "swift-mustache",
@@ -7,7 +7,7 @@
       "location" : "https://github.com/mahdibm/swift-mustache",
       "state" : {
         "branch" : "mmbm-swift-6",
-        "revision" : "e23122de36452ff04699b0fccc9a53866250c239"
+        "revision" : "72f3279b228908c786d80289e7260439163654f2"
       }
     },
     {
diff --git a/Sources/EnumeratorMacro/EnumCase.swift b/Sources/EnumeratorMacro/EnumCase.swift
index 3b366ea..b667b8c 100644
--- a/Sources/EnumeratorMacro/EnumCase.swift
+++ b/Sources/EnumeratorMacro/EnumCase.swift
@@ -99,7 +99,7 @@ extension EnumCase.MustacheArray: MustacheTransformable {
                 } else {
                     let joined = self.underlying
                         .map { String(describing: $0) }
-                        .joined(separator: "T ")
+                        .joined(separator: ", ")
                     let string = EnumCase.MustacheString("(\(joined))")
                     return string
                 }
@@ -150,7 +150,7 @@ extension EnumCase.MustacheArrayOfOptionals: MustacheTransformable {
                     let joined = self.underlying
                         .enumerated()
                         .map { $1.map { String(describing: $0) } ?? "_unnamed_\($0)" }
-                        .joined(separator: "T ")
+                        .joined(separator: ", ")
                     let string = EnumCase.MustacheString("(\(joined))")
                     return string
                 }
@@ -197,7 +197,7 @@ extension EnumCase.Parameters: MustacheTransformable {
                     let joined = names
                         .enumerated()
                         .map { $1?.underlying ?? "_unnamed_\($0)" }
-                        .joined(separator: "T ")
+                        .joined(separator: ", ")
                     let string = EnumCase.MustacheString("(\(joined))")
                     return string
                 }
diff --git a/Sources/EnumeratorMacro/EnumeratorMacroType.swift b/Sources/EnumeratorMacro/EnumeratorMacroType.swift
index a997388..45b17f8 100644
--- a/Sources/EnumeratorMacro/EnumeratorMacroType.swift
+++ b/Sources/EnumeratorMacro/EnumeratorMacroType.swift
@@ -1,6 +1,7 @@
 import SwiftDiagnostics
 import SwiftSyntax
 import SwiftSyntaxMacros
+import SwiftParser
 import Mustache
 
 public enum EnumeratorMacroType {}
@@ -14,7 +15,7 @@ extension EnumeratorMacroType: MemberMacro {
         if declaration.hasError { return [] }
 
         guard let enumDecl = declaration.as(EnumDeclSyntax.self) else {
-            fatalError("Not enum")
+            throw MacroError.isNotEnum
         }
 
         let members = enumDecl.memberBlock.members
@@ -23,7 +24,7 @@ extension EnumeratorMacroType: MemberMacro {
         let cases = try elements.map(EnumCase.init(from:))
 
         guard let arguments = node.arguments else {
-            fatalError("No arguments")
+            throw MacroError.macroDeclarationHasNoArguments
         }
         let rendered = try arguments.as(LabeledExprListSyntax.self)!.compactMap {
             $0.expression
@@ -34,8 +35,11 @@ extension EnumeratorMacroType: MemberMacro {
         }.map { template in
             try MustacheTemplate(string: "{{%CONTENT_TYPE:TEXT}}\n" + template)
                 .render(["cases": cases])
-        }.map(DeclSyntax.init(stringLiteral:))
-        
+        }.map {
+            var parser = Parser($0)
+            return DeclSyntax.parse(from: &parser)
+        }
+
         return rendered
     }
 }
diff --git a/Sources/EnumeratorMacro/MacroError.swift b/Sources/EnumeratorMacro/MacroError.swift
new file mode 100644
index 0000000..e8a1e82
--- /dev/null
+++ b/Sources/EnumeratorMacro/MacroError.swift
@@ -0,0 +1,30 @@
+import SwiftDiagnostics
+import SwiftSyntax
+
+enum MacroError: Error, CustomStringConvertible {
+    case isNotEnum
+    case macroDeclarationHasNoArguments
+
+    var description: String {
+        switch self {
+        case .isNotEnum:
+            "Only enums are supported."
+        case .macroDeclarationHasNoArguments:
+            "The macro declaration needs to have at least 1 StringLiteral argument."
+        }
+    }
+}
+
+extension MacroError: DiagnosticMessage {
+    var message: String {
+        self.description
+    }
+
+    var diagnosticID: MessageID {
+        .init(domain: "EnumeratorMacro.MacroError", id: self.description)
+    }
+
+    var severity: DiagnosticSeverity {
+        .error
+    }
+}
diff --git a/Tests/EnumeratorMacroTests/EnumeratorMacroTests.swift b/Tests/EnumeratorMacroTests/EnumeratorMacroTests.swift
index 4b7a341..159b6e0 100644
--- a/Tests/EnumeratorMacroTests/EnumeratorMacroTests.swift
+++ b/Tests/EnumeratorMacroTests/EnumeratorMacroTests.swift
@@ -4,7 +4,7 @@ import SwiftSyntaxMacrosTestSupport
 import Testing
 
 @Suite struct EnumeratorMacroTests {
-    @Test func works() throws {
+    @Test func createsCaseName() throws {
         assertMacroExpansionWithSwiftTesting(
             #"""
             @Enumerator(
@@ -42,6 +42,96 @@ import Testing
             macros: EnumeratorMacroEntryPoint.macros
         )
     }
+
+    @Test func createsACopyOfSelf() throws {
+        assertMacroExpansionWithSwiftTesting(
+            #"""
+            @Enumerator("""
+            enum CopyOfSelf {
+            {{#cases}}
+            case {{name}}{{joinedWithParenthesis(namesWithTypes(parameters))}}
+            {{/cases}}
+            }
+            """)
+            public enum TestEnum {
+                case a(val1: String, val2: Int)
+                case b
+                case testCase(testValue: String)
+            }
+            """#,
+            expandedSource: #"""
+            public enum TestEnum {
+                case a(val1: String, val2: Int)
+                case b
+                case testCase(testValue: String)
+
+                enum CopyOfSelf {
+                    case a(val1: String, val2: Int)
+                    case b
+                    case testCase(testValue: String)
+                }
+            }
+            """#,
+            macros: EnumeratorMacroEntryPoint.macros
+        )
+    }
+
+    @Test func createsDeclarationsForCaseChecking() throws {
+        assertMacroExpansionWithSwiftTesting(
+            #"""
+            @Enumerator("""
+            {{#cases}}
+            var is{{capitalized(name)}}: Bool {
+                switch self {
+                case .{{name}}:
+                    return true
+                default:
+                    return false
+                }
+            }
+            {{/cases}}
+            """)
+            public enum TestEnum {
+                case a(val1: String, val2: Int)
+                case b
+                case testCase(testValue: String)
+            }
+            """#,
+            expandedSource: #"""
+            public enum TestEnum {
+                case a(val1: String, val2: Int)
+                case b
+                case testCase(testValue: String)
+
+                var isA: Bool {
+                    switch self {
+                    case .a:
+                        return true
+                    default:
+                        return false
+                    }
+                }
+                var isB: Bool {
+                    switch self {
+                    case .b:
+                        return true
+                    default:
+                        return false
+                    }
+                }
+                var isTestcase: Bool {
+                    switch self {
+                    case .testCase:
+                        return true
+                    default:
+                        return false
+                    }
+                }
+            }
+            """#,
+            macros: EnumeratorMacroEntryPoint.macros
+        )
+    }
 }
 
 @attached(member, names: arbitrary)
@@ -50,27 +140,6 @@ macro Enumerator(_ templates: String...) = #externalMacro(
     type: "EnumeratorMacroType"
 )
 
-
-
-
-/// {{#namesWithTypes(parameters)}}{{joined(.)}}{{/namesWithTypes(parameters)}}
-
-@Enumerator("""
-enum CopyOfSelf: String {
-{{#cases}}
-case {{name}}{{#namesWithTypes(parameters)}}{{joined(.)}}{{/namesWithTypes(parameters)}}
-{{/cases}}
-}
-""")
-public enum TestEnum2 {
-    case a(val1: String, val2: Int)
-    case b
-    case testCase(testValue: String)
-}
-
-
-
-
 @Enumerator("""
 enum Subtype: String {
 {{#cases}}