diff --git a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Literals_calculateIndexOf_Test.java b/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Literals_calculateNewIndexOf_Test.java
similarity index 86%
rename from com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Literals_calculateIndexOf_Test.java
rename to com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Literals_calculateNewIndexOf_Test.java
index 8fcf9ad..2ca6260 100644
--- a/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Literals_calculateIndexOf_Test.java
+++ b/com.google.eclipse.protobuf.ui.test/src/com/google/eclipse/protobuf/ui/util/Literals_calculateNewIndexOf_Test.java
@@ -19,11 +19,11 @@
 import com.google.eclipse.protobuf.protobuf.Literal;
 
 /**
- * Tests for <code>{@link Literals#calculateIndexOf(Literal)}</code>.
+ * Tests for <code>{@link Literals#calculateNewIndexOf(Literal)}</code>.
  *
  * @author alruiz@google.com (Alex Ruiz)
  */
-public class Literals_calculateIndexOf_Test {
+public class Literals_calculateNewIndexOf_Test {
   @Rule public XtextRule xtext = overrideRuntimeModuleWith(unitTestModule());
 
   private Literals literals;
@@ -39,7 +39,7 @@
   // }
   @Test public void should_return_zero_for_first_and_only_literal() {
     Literal mobile = xtext.find("MOBILE", Literal.class);
-    long index = literals.calculateIndexOf(mobile);
+    long index = literals.calculateNewIndexOf(mobile);
     assertThat(index, equalTo(0L));
   }
 
@@ -52,7 +52,7 @@
   // }
   @Test public void should_return_max_index_value_plus_one_for_new_literal() {
     Literal work = xtext.find("WORK", Literal.class);
-    long index = literals.calculateIndexOf(work);
+    long index = literals.calculateNewIndexOf(work);
     assertThat(index, equalTo(6L));
   }
 }
diff --git a/com.google.eclipse.protobuf.ui/plugin.xml b/com.google.eclipse.protobuf.ui/plugin.xml
index 8498bdc..54a8999 100644
--- a/com.google.eclipse.protobuf.ui/plugin.xml
+++ b/com.google.eclipse.protobuf.ui/plugin.xml
@@ -30,7 +30,7 @@
       </activeWhen>
     </handler>
     <handler
-      class="com.google.eclipse.protobuf.ui.ProtobufExecutableExtensionFactory:com.google.eclipse.protobuf.ui.commands.SmartSemicolonHandler"
+      class="com.google.eclipse.protobuf.ui.ProtobufExecutableExtensionFactory:com.google.eclipse.protobuf.ui.commands.semicolon.SmartSemicolonHandler"
       commandId="com.google.eclipse.protobuf.ui.smartSemicolon">
       <activeWhen>
         <reference definitionId="com.google.eclipse.protobuf.Protobuf.Editor.opened">
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/semicolon/CommentNodesFinder.java b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/semicolon/CommentNodesFinder.java
new file mode 100644
index 0000000..059a2c6
--- /dev/null
+++ b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/semicolon/CommentNodesFinder.java
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2011 Google Inc.
+ *
+ * All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse
+ * Public License v1.0 which accompanies this distribution, and is available at
+ *
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+package com.google.eclipse.protobuf.ui.commands.semicolon;
+
+import static com.google.common.collect.Lists.newArrayList;
+import static com.google.eclipse.protobuf.util.SystemProperties.lineSeparator;
+import static java.util.regex.Pattern.CASE_INSENSITIVE;
+import static org.eclipse.xtext.nodemodel.util.NodeModelUtils.getNode;
+import static org.eclipse.xtext.util.Strings.isEmpty;
+import static org.eclipse.xtext.util.Tuples.pair;
+
+import java.util.List;
+import java.util.regex.*;
+
+import org.eclipse.emf.ecore.EObject;
+import org.eclipse.xtext.nodemodel.*;
+import org.eclipse.xtext.util.*;
+
+import com.google.eclipse.protobuf.model.util.INodes;
+import com.google.inject.*;
+
+/**
+ * @author alruiz@google.com (Alex Ruiz)
+ */
+@Singleton class CommentNodesFinder {
+  private static final String MATCH_ANYTHING = ".*";
+
+  @Inject private INodes nodes;
+  @Inject private final IResourceScopeCache cache = IResourceScopeCache.NullImpl.INSTANCE;
+
+  Pair<INode, Matcher> matchingCommentNode(EObject target, String... patternsToMatch) {
+    ICompositeNode node = getNode(target);
+    for (INode currentNode : node.getAsTreeIterable()) {
+      if (!nodes.isHiddenLeafNode(currentNode) || !nodes.isComment(currentNode)) {
+        continue;
+      }
+      String rawComment = ((ILeafNode) currentNode).getText();
+      if (isEmpty(rawComment)) {
+        continue;
+      }
+      String[] comment = rawComment.split(lineSeparator());
+      for (String line : comment) {
+        for (Pattern pattern : compile(patternsToMatch, target)) {
+          Matcher matcher = pattern.matcher(line);
+          if (matcher.matches()) { return pair(currentNode, matcher); }
+        }
+      }
+    }
+    return null;
+  }
+
+  private List<Pattern> compile(String[] patterns, EObject target) {
+    List<Pattern> compiled = newArrayList();
+    for (final String s : patterns) {
+      Pattern p = cache.get(s, target.eResource(), new Provider<Pattern>() {
+        @Override public Pattern get() {
+          return Pattern.compile(MATCH_ANYTHING + s + MATCH_ANYTHING, CASE_INSENSITIVE);
+        }
+      });
+      compiled.add(p);
+    }
+    return compiled;
+  }
+}
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/semicolon/SmartSemicolonHandler.java
similarity index 60%
rename from com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/SmartSemicolonHandler.java
rename to com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/semicolon/SmartSemicolonHandler.java
index 455003e..20a69a4 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/semicolon/SmartSemicolonHandler.java
@@ -6,16 +6,17 @@
  *
  * http://www.eclipse.org/legal/epl-v10.html
  */
-package com.google.eclipse.protobuf.ui.commands;
+package com.google.eclipse.protobuf.ui.commands.semicolon;
 
 import static com.google.eclipse.protobuf.protobuf.ProtobufPackage.Literals.*;
 import static java.util.regex.Pattern.compile;
 import static org.eclipse.xtext.util.Strings.isEmpty;
 
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.regex.*;
 
 import org.apache.log4j.Logger;
-import org.eclipse.emf.ecore.EObject;
+import org.eclipse.emf.ecore.*;
 import org.eclipse.jface.text.BadLocationException;
 import org.eclipse.swt.custom.StyledText;
 import org.eclipse.xtext.nodemodel.INode;
@@ -31,6 +32,7 @@
 import com.google.eclipse.protobuf.grammar.CommonKeyword;
 import com.google.eclipse.protobuf.model.util.*;
 import com.google.eclipse.protobuf.protobuf.*;
+import com.google.eclipse.protobuf.ui.commands.SmartInsertHandler;
 import com.google.eclipse.protobuf.ui.preferences.editor.numerictag.core.NumericTagPreferences;
 import com.google.eclipse.protobuf.ui.util.Literals;
 import com.google.inject.Inject;
@@ -45,6 +47,10 @@
 public class SmartSemicolonHandler extends SmartInsertHandler {
   private static final Pattern NUMBERS_PATTERN = compile("[\\d]+");
 
+  private static final IUnitOfWork.Void<XtextResource> NULL_UNIT_OF_WORK = new IUnitOfWork.Void<XtextResource>() {
+    @Override public void process(XtextResource resource) {}
+  };
+
   private static Logger logger = Logger.getLogger(SmartSemicolonHandler.class);
 
   @Inject private CommentNodesFinder commentNodesFinder;
@@ -56,36 +62,29 @@
 
   private static final String SEMICOLON = CommonKeyword.SEMICOLON.toString();
 
-  private static final ContentToInsert INSERT_SEMICOLON_AT_CURRENT_LOCATION = new ContentToInsert(SEMICOLON, Location.CURRENT);
-
-  /** {@inheritDoc} */
   @Override protected void insertContent(XtextEditor editor, StyledText styledText) {
-    int offset = styledText.getCaretOffset();
-    int lineAtOffset = styledText.getLineAtOffset(offset);
-    int offsetAtLine = styledText.getOffsetAtLine(lineAtOffset);
-    String line = styledText.getLine(lineAtOffset);
-    ContentToInsert newContent = newContent(editor, styledText, line);
-    if (newContent.equals(ContentToInsert.TAG_NUMBER_INSERTED)) {
-      refreshHighlighting(editor);
+    StyledTextAccess styledTextAccess = new StyledTextAccess(styledText);
+    String line = styledTextAccess.lineAtCaretOffset();
+    if (line.endsWith(SEMICOLON)) {
+      styledTextAccess.insert(SEMICOLON);
       return;
     }
-    if (newContent.location.equals(Location.END)) {
-      offset = offsetAtLine + line.length();
-      styledText.setCaretOffset(offset);
-    }
-    styledText.insert(newContent.value);
-    styledText.setCaretOffset(offset + newContent.value.length());
+    waitForReconcilerToFinishWork(editor);
+    insertContent(editor, styledTextAccess);
+    refreshHighlighting(editor);
   }
 
-  private ContentToInsert newContent(final XtextEditor editor, final StyledText styledText, final String line) {
-    if (line.endsWith(SEMICOLON)) {
-      return INSERT_SEMICOLON_AT_CURRENT_LOCATION;
-    }
+  private void waitForReconcilerToFinishWork(XtextEditor editor) {
+    editor.getDocument().readOnly(NULL_UNIT_OF_WORK);
+  }
+
+  private void insertContent(final XtextEditor editor, final StyledTextAccess styledTextAccess) {
+    final AtomicBoolean shouldInsertSemicolon = new AtomicBoolean(true);
     final IXtextDocument document = editor.getDocument();
     try {
-      return document.modify(new IUnitOfWork<ContentToInsert, XtextResource>() {
-        @Override public ContentToInsert exec(XtextResource resource) {
-          int offset = styledText.getCaretOffset();
+      document.modify(new IUnitOfWork.Void<XtextResource>() {
+        @Override public void process(XtextResource resource) {
+          int offset = styledTextAccess.caretOffset();
           ContentAssistContext[] context = contextFactory.create(editor.getInternalSourceViewer(), offset, resource);
           for (ContentAssistContext c : context) {
             if (nodes.isCommentOrString(c.getCurrentNode())) {
@@ -98,63 +97,46 @@
             }
             if (model instanceof Literal) {
               Literal literal = (Literal) model;
-              ContentToInsert content = newContent(literal);
-              if (content.equals(ContentToInsert.TAG_NUMBER_INSERTED)) {
-                long index = literals.calculateIndexOf(literal);
+              if (shouldCalculateIndex(literal, LITERAL__INDEX)) {
+                long index = literals.calculateNewIndexOf(literal);
                 literal.setIndex(index);
                 updateIndexInCommentOfParent(literal, index, document);
+                shouldInsertSemicolon.set(false);
               }
-              return content;
             }
             if (model instanceof MessageField) {
               MessageField field = (MessageField) model;
-              ContentToInsert content = newContent(field);
-              if (content.equals(ContentToInsert.TAG_NUMBER_INSERTED)) {
+              if (shouldCalculateIndex(field, MESSAGE_FIELD__INDEX)) {
                 long index = indexedElements.calculateNewIndexFor(field);
                 field.setIndex(index);
                 updateIndexInCommentOfParent(field, index, document);
+                shouldInsertSemicolon.set(false);
               }
-              return content;
             }
           }
-          return INSERT_SEMICOLON_AT_CURRENT_LOCATION;
         }
       });
-    } catch (Throwable e) {
-      logger.error("Unable to generate tag number", e);
-      return INSERT_SEMICOLON_AT_CURRENT_LOCATION;
+    } catch (Throwable t) {
+      logger.error("Unable to generate tag number", t);
     }
+    if (shouldInsertSemicolon.get()) {
+      styledTextAccess.insert(SEMICOLON);
+    }
+  }
+
+  private boolean shouldCalculateIndex(EObject target, EAttribute indexAttribute) {
+    INode node = nodes.firstNodeForFeature(target, indexAttribute);
+    return node == null || isEmpty(node.getText());
   }
 
   private EObject modelFrom(ContentAssistContext c) {
     EObject current = c.getCurrentModel();
-    if (isIndexed(current)) {
-      return current;
-    }
-    return c.getPreviousModel();
+    boolean isIndexed = current instanceof MessageField || current instanceof Literal;
+    return (isIndexed) ? current : c.getPreviousModel();
   }
 
-  private boolean isIndexed(EObject e) {
-    return e instanceof MessageField || e instanceof Literal;
-  }
-
-  private ContentToInsert newContent(Literal literal) {
-    INode indexNode = nodes.firstNodeForFeature(literal, LITERAL__INDEX);
-    return newContent(indexNode);
-  }
-
-  private ContentToInsert newContent(MessageField field) {
-    INode indexNode = nodes.firstNodeForFeature(field, MESSAGE_FIELD__INDEX);
-    return newContent(indexNode);
-  }
-
-  private ContentToInsert newContent(INode indexNode) {
-    boolean hasIndex = indexNode != null && !isEmpty(indexNode.getText());
-    return hasIndex ? new ContentToInsert(SEMICOLON, Location.END) : ContentToInsert.TAG_NUMBER_INSERTED;
-  }
-
-  private void updateIndexInCommentOfParent(EObject o, long index, IXtextDocument document) {
-    EObject parent = o.eContainer();
+  private void updateIndexInCommentOfParent(EObject target, long index, IXtextDocument document) {
+    EObject parent = target.eContainer();
     if (parent == null) {
       return;
     }
@@ -184,28 +166,4 @@
       }
     });
   }
-
-  private static class ContentToInsert {
-    final String value;
-    final Location location;
-
-    static final ContentToInsert TAG_NUMBER_INSERTED = new ContentToInsert();
-
-    ContentToInsert() {
-      this("", Location.NONE);
-    }
-
-    ContentToInsert(String value, Location location) {
-      this.value = value;
-      this.location = location;
-    }
-
-    @Override public String toString() {
-      return String.format("ContentToInsert [value=%s, location=%s]", value, location);
-    }
-  }
-
-  private static enum Location {
-    NONE, CURRENT, END;
-  }
 }
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/semicolon/StyledTextAccess.java b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/semicolon/StyledTextAccess.java
new file mode 100644
index 0000000..2f6bfda
--- /dev/null
+++ b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/commands/semicolon/StyledTextAccess.java
@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2012 Google Inc.
+ *
+ * All rights reserved. This program and the accompanying materials are made available under the terms of the Eclipse
+ * Public License v1.0 which accompanies this distribution, and is available at
+ *
+ * http://www.eclipse.org/legal/epl-v10.html
+ */
+package com.google.eclipse.protobuf.ui.commands.semicolon;
+
+import org.eclipse.swt.custom.StyledText;
+
+/**
+ * @author alruiz@google.com (Alex Ruiz)
+ */
+class StyledTextAccess {
+  private final StyledText styledText;
+
+  StyledTextAccess(StyledText styledText) {
+    this.styledText = styledText;
+  }
+
+  String lineAtCaretOffset() {
+    int offset = caretOffset();
+    int lineAtOffset = styledText.getLineAtOffset(offset);
+    return styledText.getLine(lineAtOffset);
+  }
+
+  void setCaretOffsetToEndOfLine() {
+    int offset = caretOffset();
+    int lineAtOffset = styledText.getLineAtOffset(offset);
+    String line = styledText.getLine(lineAtOffset);
+    int offsetAtLine = styledText.getOffsetAtLine(lineAtOffset);
+    offset = offsetAtLine + line.length();
+    styledText.setCaretOffset(offset);
+  }
+
+  void insert(String text) {
+    styledText.insert(text);
+    styledText.setCaretOffset(caretOffset() + text.length());
+  }
+
+  int caretOffset() {
+    return styledText.getCaretOffset();
+  }
+}
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 7e6dadb..6da38e0 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
@@ -282,7 +282,7 @@
 
   @Override public void completeLiteral_Index(EObject model, Assignment assignment, ContentAssistContext context,
       ICompletionProposalAcceptor acceptor) {
-    long index = literals.calculateIndexOf((Literal) model);
+    long index = literals.calculateNewIndexOf((Literal) model);
     proposeIndex(index, context, acceptor);
   }
 
diff --git a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Literals.java b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Literals.java
index 0dcf2ea..d962ed8 100644
--- a/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Literals.java
+++ b/com.google.eclipse.protobuf.ui/src/com/google/eclipse/protobuf/ui/util/Literals.java
@@ -43,7 +43,7 @@
    *          the given literal.
    * @return the calculated index value.
    */
-  public long calculateIndexOf(Literal l) {
+  public long calculateNewIndexOf(Literal l) {
     long index = -1;
     List<Literal> allLiterals = getAllContentsOfType(l.eContainer(), Literal.class);
     for (Literal c : allLiterals) {