diff --git a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CommonKeyword_hasValue_Test.java b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/grammar/CommonKeyword_hasValue_Test.java
similarity index 91%
rename from com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CommonKeyword_hasValue_Test.java
rename to com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/grammar/CommonKeyword_hasValue_Test.java
index 902a757..0e0da1f 100644
--- a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CommonKeyword_hasValue_Test.java
+++ b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/grammar/CommonKeyword_hasValue_Test.java
@@ -6,9 +6,9 @@
  *
  * http://www.eclipse.org/legal/epl-v10.html
  */
-package com.google.eclipse.protobuf.ui.grammar;
+package com.google.eclipse.protobuf.grammar;
 
-import static com.google.eclipse.protobuf.ui.grammar.CommonKeyword.*;
+import static com.google.eclipse.protobuf.grammar.CommonKeyword.*;
 import static org.hamcrest.core.IsEqual.equalTo;
 import static org.junit.Assert.assertThat;
 
diff --git a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CommonKeyword_toString_Test.java b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/grammar/CommonKeyword_toString_Test.java
similarity index 84%
rename from com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CommonKeyword_toString_Test.java
rename to com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/grammar/CommonKeyword_toString_Test.java
index 9895bfc..50ec6f0 100644
--- a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CommonKeyword_toString_Test.java
+++ b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/grammar/CommonKeyword_toString_Test.java
@@ -6,9 +6,9 @@
  *
  * http://www.eclipse.org/legal/epl-v10.html
  */
-package com.google.eclipse.protobuf.ui.grammar;
+package com.google.eclipse.protobuf.grammar;
 
-import static com.google.eclipse.protobuf.ui.grammar.CommonKeyword.BOOL;
+import static com.google.eclipse.protobuf.grammar.CommonKeyword.BOOL;
 import static org.hamcrest.core.IsEqual.equalTo;
 import static org.junit.Assert.assertThat;
 
diff --git a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_isBool_Test.java b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_isBool_Test.java
similarity index 97%
rename from com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_isBool_Test.java
rename to com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_isBool_Test.java
index 54930eb..e30879e 100644
--- a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_isBool_Test.java
+++ b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_isBool_Test.java
@@ -6,7 +6,7 @@
  *
  * http://www.eclipse.org/legal/epl-v10.html
  */
-package com.google.eclipse.protobuf.ui.util;
+package com.google.eclipse.protobuf.util;
 
 import static com.google.eclipse.protobuf.junit.util.Finder.findProperty;
 import static org.hamcrest.core.IsEqual.equalTo;
diff --git a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_isPrimitive_Test.java b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_isPrimitive_Test.java
similarity index 97%
rename from com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_isPrimitive_Test.java
rename to com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_isPrimitive_Test.java
index db24e18..384664d 100644
--- a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_isPrimitive_Test.java
+++ b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_isPrimitive_Test.java
@@ -6,7 +6,7 @@
  *
  * http://www.eclipse.org/legal/epl-v10.html
  */
-package com.google.eclipse.protobuf.ui.util;
+package com.google.eclipse.protobuf.util;
 
 import static com.google.eclipse.protobuf.junit.util.Finder.allProperties;
 import static org.hamcrest.core.IsEqual.equalTo;
diff --git a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_isString_Test.java b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_isString_Test.java
similarity index 97%
rename from com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_isString_Test.java
rename to com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_isString_Test.java
index 4ef01fc..595b89b 100644
--- a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_isString_Test.java
+++ b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_isString_Test.java
@@ -6,7 +6,7 @@
  *
  * http://www.eclipse.org/legal/epl-v10.html
  */
-package com.google.eclipse.protobuf.ui.util;
+package com.google.eclipse.protobuf.util;
 
 import static com.google.eclipse.protobuf.junit.util.Finder.findProperty;
 import static org.hamcrest.core.IsEqual.equalTo;
diff --git a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_typeNameOf_Test.java b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_typeNameOf_Test.java
similarity index 97%
rename from com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_typeNameOf_Test.java
rename to com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_typeNameOf_Test.java
index 8b50b0d..1a08d4b 100644
--- a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Properties_typeNameOf_Test.java
+++ b/com.google.eclipse.protobuf.test/src/com/google/eclipse/protobuf/util/Properties_typeNameOf_Test.java
@@ -6,7 +6,7 @@
  *
  * http://www.eclipse.org/legal/epl-v10.html
  */
-package com.google.eclipse.protobuf.ui.util;
+package com.google.eclipse.protobuf.util;
 
 import static com.google.eclipse.protobuf.junit.util.Finder.findProperty;
 import static org.hamcrest.core.IsEqual.equalTo;
diff --git a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CompoundElement_indexOf_Test.java b/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CompoundElement_indexOf_Test.java
index 15ef28d..647bbdf 100644
--- a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CompoundElement_indexOf_Test.java
+++ b/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/grammar/CompoundElement_indexOf_Test.java
@@ -8,13 +8,15 @@
  */
 package com.google.eclipse.protobuf.ui.grammar;
 
-import static com.google.eclipse.protobuf.ui.grammar.CommonKeyword.*;
+import static com.google.eclipse.protobuf.grammar.CommonKeyword.*;
 import static com.google.eclipse.protobuf.ui.grammar.CompoundElement.DEFAULT_EQUAL;
 import static org.hamcrest.core.IsEqual.equalTo;
 import static org.junit.Assert.assertThat;
 
 import org.junit.Test;
 
+import com.google.eclipse.protobuf.grammar.CommonKeyword;
+
 /**
  * Tests for <code>{@link CompoundElement#indexOf(CommonKeyword)}</code>.
  *
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/SmartSemicolonHandler.java b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/SmartSemicolonHandler.java
index 6f52c7e..35c6bf8 100644
--- a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/SmartSemicolonHandler.java
+++ b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/SmartSemicolonHandler.java
@@ -8,7 +8,7 @@
  */
 package com.google.eclipse.protobuf.ui.commands;
 
-import static com.google.eclipse.protobuf.ui.grammar.CommonKeyword.SEMICOLON;
+import static com.google.eclipse.protobuf.grammar.CommonKeyword.SEMICOLON;
 
 import java.util.regex.Pattern;
 
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/contentassist/ProtobufProposalProvider.java b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/contentassist/ProtobufProposalProvider.java
index ed93126..d74ff54 100644
--- a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/contentassist/ProtobufProposalProvider.java
+++ b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/contentassist/ProtobufProposalProvider.java
@@ -8,15 +8,15 @@
  */
 package com.google.eclipse.protobuf.ui.contentassist;
 
+import static com.google.eclipse.protobuf.grammar.CommonKeyword.*;
 import static com.google.eclipse.protobuf.protobuf.Modifier.*;
-import static com.google.eclipse.protobuf.protobuf.ScalarType.STRING;
-import static com.google.eclipse.protobuf.ui.grammar.CommonKeyword.*;
 import static com.google.eclipse.protobuf.ui.grammar.CompoundElement.*;
 import static com.google.eclipse.protobuf.ui.util.Strings.firstCharToLowerCase;
 import static java.lang.String.valueOf;
 import static java.util.Collections.emptyList;
 
-import java.util.*;
+import java.util.ArrayList;
+import java.util.List;
 
 import org.eclipse.emf.ecore.EObject;
 import org.eclipse.jface.text.contentassist.ICompletionProposal;
@@ -27,14 +27,16 @@
 import org.eclipse.xtext.ui.editor.contentassist.*;
 
 import com.google.common.collect.ImmutableList;
+import com.google.eclipse.protobuf.grammar.CommonKeyword;
 import com.google.eclipse.protobuf.protobuf.*;
 import com.google.eclipse.protobuf.protobuf.Enum;
-import com.google.eclipse.protobuf.scoping.*;
-import com.google.eclipse.protobuf.ui.grammar.*;
+import com.google.eclipse.protobuf.scoping.ProtoDescriptor;
+import com.google.eclipse.protobuf.scoping.ProtoDescriptorProvider;
 import com.google.eclipse.protobuf.ui.grammar.CompoundElement;
 import com.google.eclipse.protobuf.ui.labeling.Images;
-import com.google.eclipse.protobuf.ui.util.*;
-import com.google.eclipse.protobuf.ui.util.Properties;
+import com.google.eclipse.protobuf.ui.util.Fields;
+import com.google.eclipse.protobuf.ui.util.Literals;
+import com.google.eclipse.protobuf.util.Properties;
 import com.google.eclipse.protobuf.util.ProtobufElementFinder;
 import com.google.inject.Inject;
 
@@ -131,7 +133,7 @@
       ICompletionProposalAcceptor acceptor) {
     if (model instanceof Property && isProposalForDefaultValue(context)) {
       Property p = (Property) model;
-      if (!isStringProperty(p)) return;
+      if (!properties.isString(p)) return;
       proposeEmptyString(context, acceptor);
       return;
     }
@@ -223,7 +225,7 @@
     if (OPTIONAL.equals(modifier)) {
       CompoundElement display = DEFAULT_EQUAL_IN_BRACKETS;
       int cursorPosition = display.indexOf(CLOSING_BRACKET);
-      if (isStringProperty(p)) {
+      if (properties.isString(p)) {
         display = DEFAULT_EQUAL_STRING_IN_BRACKETS;
         cursorPosition++;
       }
@@ -243,7 +245,7 @@
     CompoundElement display = DEFAULT_EQUAL;
     int cursorPosition = display.charCount();
     Property property = extractPropertyFrom(context);
-    if (isStringProperty(property)) {
+    if (properties.isString(property)) {
       display = DEFAULT_EQUAL_STRING;
       cursorPosition++;
     }
@@ -277,10 +279,6 @@
     return type.cast(model);
   }
 
-  private boolean isStringProperty(Property p) {
-    return STRING.equals(finder.scalarTypeOf(p));
-  }
-
   private ICompletionProposal createCompletionProposal(CompoundElement proposal, ContentAssistContext context) {
     return createCompletionProposal(proposal.toString(), context);
   }
@@ -398,6 +396,7 @@
 
   @Override public void completeFieldOption_Value(EObject model, Assignment assignment, ContentAssistContext context,
       ICompletionProposalAcceptor acceptor) {
+    if (!(model instanceof FieldOption)) return;
     FieldOption option = (FieldOption) model;
     ProtoDescriptor descriptor = descriptorProvider.get();
     Enum enumType = descriptor.enumTypeOf(option);
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/grammar/CompoundElement.java b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/grammar/CompoundElement.java
index 418b253..62b1046 100644
--- a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/grammar/CompoundElement.java
+++ b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/grammar/CompoundElement.java
@@ -8,7 +8,9 @@
  */
 package com.google.eclipse.protobuf.ui.grammar;
 
-import static com.google.eclipse.protobuf.ui.grammar.CommonKeyword.*;
+import static com.google.eclipse.protobuf.grammar.CommonKeyword.*;
+
+import com.google.eclipse.protobuf.grammar.CommonKeyword;
 
 /**
  * Element composed of one or more keywords.
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/labeling/Labels.java b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/labeling/Labels.java
index d8319e4..ae469a2 100644
--- a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/labeling/Labels.java
+++ b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/labeling/Labels.java
@@ -12,8 +12,8 @@
 import static org.eclipse.jface.viewers.StyledString.DECORATIONS_STYLER;
 
 import com.google.eclipse.protobuf.protobuf.*;
-import com.google.eclipse.protobuf.ui.util.Properties;
 import com.google.eclipse.protobuf.util.ModelNodes;
+import com.google.eclipse.protobuf.util.Properties;
 import com.google.inject.*;
 
 import org.eclipse.jface.viewers.StyledString;
diff --git a/com.google.eclipse.protobuf/META-INF/MANIFEST.MF b/com.google.eclipse.protobuf/META-INF/MANIFEST.MF
index f4159fc..be7f077 100644
--- a/com.google.eclipse.protobuf/META-INF/MANIFEST.MF
+++ b/com.google.eclipse.protobuf/META-INF/MANIFEST.MF
@@ -21,6 +21,7 @@
  org.apache.commons.logging
 Bundle-RequiredExecutionEnvironment: J2SE-1.5
 Export-Package: com.google.eclipse.protobuf,
+ com.google.eclipse.protobuf.grammar,
  com.google.eclipse.protobuf.parseTreeConstruction,
  com.google.eclipse.protobuf.parser.antlr,
  com.google.eclipse.protobuf.parser.antlr.internal,
diff --git a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/Protobuf.xtext b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/Protobuf.xtext
index a14878e..0f0c32e 100644
--- a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/Protobuf.xtext
+++ b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/Protobuf.xtext
@@ -108,7 +108,9 @@
   | BooleanRef
   | IntRef
   | FloatRef
-  | StringRef;
+  | DoubleRef
+  | StringRef
+  | Nan;
 
 LiteralRef:
   literal=[Literal];
@@ -126,9 +128,15 @@
 FloatRef:
   float=FLOAT;
 
+DoubleRef:
+  double=DOUBLE;
+
 StringRef:
   string=STRING;
 
+Nan:
+  number='nan';
+
 Enum:
   'enum' name=Name '{'
   literals+=Literal*
@@ -163,4 +171,5 @@
 
 terminal INT returns ecore::EInt: ('-')? ('0'..'9')+;  
 terminal FLOAT returns ecore::EFloat: ('-')? ('0'..'9')* ('.' ('0'..'9')+)?;
+terminal DOUBLE returns ecore::EDouble: ('-')? ('0'..'9')* ('.' ('0'..'9')+)?;
   
\ No newline at end of file
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/grammar/CommonKeyword.java b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/grammar/CommonKeyword.java
similarity index 96%
rename from com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/grammar/CommonKeyword.java
rename to com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/grammar/CommonKeyword.java
index 0807913..d00648c 100644
--- a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/grammar/CommonKeyword.java
+++ b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/grammar/CommonKeyword.java
@@ -6,7 +6,7 @@
  *
  * http://www.eclipse.org/legal/epl-v10.html
  */
-package com.google.eclipse.protobuf.ui.grammar;
+package com.google.eclipse.protobuf.grammar;
 
 /**
  * A commonly used keyword.
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Properties.java b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/util/Properties.java
similarity index 93%
rename from com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Properties.java
rename to com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/util/Properties.java
index f9668cd..3ddcd47 100644
--- a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Properties.java
+++ b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/util/Properties.java
@@ -6,12 +6,12 @@
  *
  * http://www.eclipse.org/legal/epl-v10.html
  */
-package com.google.eclipse.protobuf.ui.util;
+package com.google.eclipse.protobuf.util;
 
-import static com.google.eclipse.protobuf.ui.grammar.CommonKeyword.*;
+import static com.google.eclipse.protobuf.grammar.CommonKeyword.*;
 
+import com.google.eclipse.protobuf.grammar.CommonKeyword;
 import com.google.eclipse.protobuf.protobuf.*;
-import com.google.eclipse.protobuf.ui.grammar.CommonKeyword;
 import com.google.inject.Singleton;
 
 /**
diff --git a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/Messages.java b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/Messages.java
index cbd6fa0..7bbe1d8 100644
--- a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/Messages.java
+++ b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/Messages.java
@@ -17,7 +17,9 @@
 
   public static String expectedFieldName;
   public static String expectedFieldNumber;
+  public static String expectedString;
   public static String expectedSyntaxIdentifier;
+  public static String expectedTrueOrFalse;
   public static String fieldNumberAlreadyUsed;
   public static String fieldNumbersMustBePositive;
   public static String importNotFound;
diff --git a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/Messages.properties b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/Messages.properties
index dbb5a26..cc7c6ed 100644
--- a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/Messages.properties
+++ b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/Messages.properties
@@ -1,6 +1,8 @@
 expectedFieldName = Expected field name.
 expectedFieldNumber = Expected field number.
+expectedString = Expected string.
 expectedSyntaxIdentifier = Expected syntax identifier.
+expectedTrueOrFalse = Expected "true" or "false".
 fieldNumberAlreadyUsed = Field number %d has already been used in \"%s\" by field \"%s\".
 fieldNumbersMustBePositive = Field numbers must be positive integers.
 importNotFound = Import \"%s\" was not found.
diff --git a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/ProtobufJavaValidator.java b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/ProtobufJavaValidator.java
index 22a6323..a818e82 100644
--- a/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/ProtobufJavaValidator.java
+++ b/com.google.eclipse.protobuf/src/com/google/eclipse/protobuf/validation/ProtobufJavaValidator.java
@@ -8,6 +8,7 @@
  */
 package com.google.eclipse.protobuf.validation;
 
+import static com.google.eclipse.protobuf.protobuf.Modifier.OPTIONAL;
 import static com.google.eclipse.protobuf.protobuf.ProtobufPackage.Literals.*;
 import static com.google.eclipse.protobuf.validation.Messages.*;
 import static java.lang.String.format;
@@ -15,11 +16,13 @@
 
 import org.eclipse.emf.common.util.URI;
 import org.eclipse.emf.ecore.EObject;
-import org.eclipse.xtext.naming.*;
+import org.eclipse.xtext.naming.IQualifiedNameProvider;
+import org.eclipse.xtext.naming.QualifiedName;
 import org.eclipse.xtext.validation.Check;
 
 import com.google.eclipse.protobuf.protobuf.*;
 import com.google.eclipse.protobuf.protobuf.Package;
+import com.google.eclipse.protobuf.util.Properties;
 import com.google.inject.Inject;
 
 /**
@@ -28,6 +31,20 @@
 public class ProtobufJavaValidator extends AbstractProtobufJavaValidator {
 
   @Inject private IQualifiedNameProvider qualifiedNameProvider;
+  @Inject private Properties properties;
+
+  @Check public void checkDefaultValueType(Property property) {
+    ValueRef defaultValue = property.getDefault();
+    if (!OPTIONAL.equals(property.getModifier()) || defaultValue == null) return;
+    if (properties.isString(property)) {
+      if (defaultValue instanceof StringRef) return;
+      error(expectedString, PROPERTY__DEFAULT);
+    }
+    if (properties.isBool(property)) {
+      if (defaultValue instanceof BooleanRef) return;
+      error(expectedTrueOrFalse, PROPERTY__DEFAULT);
+    }
+  }
 
   @Check public void checkImportIsResolved(Import anImport) {
     String importUri = anImport.getImportURI();