diff --git a/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/CustomizableProperty.groovy b/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/CustomizableProperty.groovy
index 592fff82a0..fc6dfcb503 100644
--- a/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/CustomizableProperty.groovy
+++ b/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/CustomizableProperty.groovy
@@ -26,8 +26,8 @@ class CustomizableProperty<T, V> {
 class StringCustomizableProperty extends CustomizableProperty<String, String> {
 }
 
-class NoOpCustomizableProperty<T> extends CustomizableProperty<T, T> {
-    NoOpCustomizableProperty(T value) {
+class SingleTypeCustomizableProperty<T> extends CustomizableProperty<T, T> {
+    SingleTypeCustomizableProperty(T value) {
         client(value)
         server(value)
     }
diff --git a/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/Headers.groovy b/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/Headers.groovy
index 3ab38d42ec..ca7e87e7cb 100644
--- a/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/Headers.groovy
+++ b/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/Headers.groovy
@@ -11,7 +11,6 @@ class Headers {
     }
 
     Set<Map.Entry<String, WithValuePattern>> entries() {
-        //TODO: Make it immutable
-        return headers.entrySet()
+        return Collections.unmodifiableSet(headers.entrySet())
     }
 }
diff --git a/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/WithValuePattern.groovy b/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/WithValuePattern.groovy
index 5f92b4f27f..9e44935cfa 100644
--- a/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/WithValuePattern.groovy
+++ b/accurest-core/src/main/groovy/io/coderate/accurest/dsl/internal/WithValuePattern.groovy
@@ -4,11 +4,11 @@ import static io.coderate.accurest.dsl.internal.DelegateHelper.delegateToClosure
 
 class WithValuePattern {
 
-    NoOpCustomizableProperty<String> equalToJson
-    NoOpCustomizableProperty<String> equalToXml
+    SingleTypeCustomizableProperty<String> equalToJson
+    SingleTypeCustomizableProperty<String> equalToXml
     StringCustomizableProperty matchesXPath
-    NoOpCustomizableProperty<JSONCompareMode> jsonCompareMode
-    NoOpCustomizableProperty<String> equalTo
+    SingleTypeCustomizableProperty<JSONCompareMode> jsonCompareMode
+    SingleTypeCustomizableProperty<String> equalTo
     StringCustomizableProperty contains
     StringCustomizableProperty matches
     StringCustomizableProperty doesNotMatch
@@ -20,7 +20,7 @@ class WithValuePattern {
 //        }
 //
     void equalTo(String equalTo) {
-        this.equalTo = new NoOpCustomizableProperty(equalTo)
+        this.equalTo = new SingleTypeCustomizableProperty(equalTo)
     }
 
 //        void equalToXml(String equalToXml) {