diff --git a/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRenderer.java b/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRenderer.java
index 69db8d5598a..1d892326b72 100644
--- a/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRenderer.java
+++ b/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRenderer.java
@@ -55,17 +55,36 @@ public interface DescriptorRenderer extends Renderer<DeclarationDescriptor> {
         PLAIN, HTML
     }
 
+    /** @see DefaultValueParameterHandler */
     interface ValueParametersHandler {
-        // by default, renders "("
         void appendBeforeValueParameters(@NotNull FunctionDescriptor function, @NotNull StringBuilder stringBuilder);
-
-        // by default, renders ")"
         void appendAfterValueParameters(@NotNull FunctionDescriptor function, @NotNull StringBuilder stringBuilder);
 
-        // by default, renders nothing
         void appendBeforeValueParameter(@NotNull ValueParameterDescriptor parameter, @NotNull StringBuilder stringBuilder);
-
-        // by default, renders ", " if its not last parameter
         void appendAfterValueParameter(@NotNull ValueParameterDescriptor parameter, @NotNull StringBuilder stringBuilder);
     }
+
+    class DefaultValueParameterHandler implements ValueParametersHandler {
+        @Override
+        public void appendBeforeValueParameters(@NotNull FunctionDescriptor function, @NotNull StringBuilder stringBuilder) {
+            stringBuilder.append("(");
+        }
+
+        @Override
+        public void appendAfterValueParameters(@NotNull FunctionDescriptor function, @NotNull StringBuilder stringBuilder) {
+            stringBuilder.append(")");
+        }
+
+        @Override
+        public void appendBeforeValueParameter(@NotNull ValueParameterDescriptor parameter, @NotNull StringBuilder stringBuilder) {
+        }
+
+        @Override
+        public void appendAfterValueParameter(@NotNull ValueParameterDescriptor parameter, @NotNull StringBuilder stringBuilder) {
+            FunctionDescriptor function = (FunctionDescriptor) parameter.getContainingDeclaration();
+            if (parameter.getIndex() != function.getValueParameters().size() - 1) {
+                stringBuilder.append(", ");
+            }
+        }
+    }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRendererBuilder.java b/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRendererBuilder.java
index 295b899d0e9..90b45984a46 100644
--- a/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRendererBuilder.java
+++ b/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRendererBuilder.java
@@ -17,7 +17,6 @@
 package org.jetbrains.jet.renderer;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 public class DescriptorRendererBuilder {
     private boolean shortNames = false;
@@ -25,8 +24,8 @@ public class DescriptorRendererBuilder {
     private boolean modifiers = true;
     private boolean startFromName = false;
     private boolean debugMode = false;
-    @Nullable
-    private DescriptorRenderer.ValueParametersHandler valueParametersHandler = null;
+    @NotNull
+    private DescriptorRenderer.ValueParametersHandler valueParametersHandler = new DescriptorRenderer.DefaultValueParameterHandler();
     @NotNull
     private DescriptorRenderer.TextFormat textFormat = DescriptorRenderer.TextFormat.PLAIN;
 
@@ -58,7 +57,7 @@ public class DescriptorRendererBuilder {
         return this;
     }
 
-    public DescriptorRendererBuilder setValueParametersHandler(@Nullable DescriptorRenderer.ValueParametersHandler valueParametersHandler) {
+    public DescriptorRendererBuilder setValueParametersHandler(@NotNull DescriptorRenderer.ValueParametersHandler valueParametersHandler) {
         this.valueParametersHandler = valueParametersHandler;
         return this;
     }
diff --git a/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRendererImpl.java b/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRendererImpl.java
index 8ec151c3126..dc7a6d0edb8 100644
--- a/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRendererImpl.java
+++ b/compiler/frontend/src/org/jetbrains/jet/renderer/DescriptorRendererImpl.java
@@ -20,7 +20,6 @@ import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import com.intellij.psi.tree.IElementType;
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.resolve.DescriptorUtils;
 import org.jetbrains.jet.lang.resolve.name.FqName;
@@ -51,7 +50,7 @@ public class DescriptorRendererImpl implements DescriptorRenderer {
     private final boolean modifiers;
     private final boolean startFromName;
     private final boolean debugMode;
-    @Nullable
+    @NotNull
     private final ValueParametersHandler handler;
     @NotNull
     private final TextFormat textFormat;
@@ -62,7 +61,7 @@ public class DescriptorRendererImpl implements DescriptorRenderer {
             boolean modifiers,
             boolean startFromName,
             boolean debugMode,
-            @Nullable ValueParametersHandler handler,
+            @NotNull ValueParametersHandler handler,
             @NotNull TextFormat textFormat
     ) {
         this.shortNames = shortNames;
@@ -423,25 +422,13 @@ public class DescriptorRendererImpl implements DescriptorRenderer {
     }
 
     private void renderValueParameters(FunctionDescriptor function, StringBuilder builder) {
-        if (handler != null) {
-            handler.appendBeforeValueParameters(function, builder);
-            for (ValueParameterDescriptor parameter : function.getValueParameters()) {
-                handler.appendBeforeValueParameter(parameter, builder);
-                renderValueParameter(parameter, builder, false);
-                handler.appendAfterValueParameter(parameter, builder);
-            }
-            handler.appendAfterValueParameters(function, builder);
-        }
-        else {
-            builder.append("(");
-            for (ValueParameterDescriptor parameter : function.getValueParameters()) {
-                renderValueParameter(parameter, builder, false);
-                if (parameter.getIndex() != function.getValueParameters().size() - 1) {
-                    builder.append(", ");
-                }
-            }
-            builder.append(")");
+        handler.appendBeforeValueParameters(function, builder);
+        for (ValueParameterDescriptor parameter : function.getValueParameters()) {
+            handler.appendBeforeValueParameter(parameter, builder);
+            renderValueParameter(parameter, builder, false);
+            handler.appendAfterValueParameter(parameter, builder);
         }
+        handler.appendAfterValueParameters(function, builder);
     }
 
     /* VARIABLES */
@@ -634,6 +621,5 @@ public class DescriptorRendererImpl implements DescriptorRenderer {
             renderClass(descriptor, builder);
             return null;
         }
-
    }
 }
\ No newline at end of file