diff --git a/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart b/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
index 7f3e404..0e50714 100644
--- a/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
+++ b/pkg/front_end/lib/src/fasta/fasta_codes_generated.dart
@@ -4957,6 +4957,17 @@
 }
 
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<Null> codeNotAConstantExpression = messageNotAConstantExpression;
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const MessageCode messageNotAConstantExpression = const MessageCode(
+    "NotAConstantExpression",
+    analyzerCode: "NOT_CONSTANT_EXPRESSION",
+    dart2jsCode: "*fatal*",
+    severity: Severity.error,
+    message: r"""Not a constant expression.""");
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
     Message Function(
         Token token,
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 74a8d46..f84c0a6 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -1542,16 +1542,16 @@
       if (constantContext != ConstantContext.none &&
           declaration.isTypeVariable &&
           !member.isConstructor) {
-        deprecated_addCompileTimeError(
-            charOffset, "Not a constant expression.");
+        addCompileTimeError(
+            fasta.messageNotAConstantExpression, charOffset, token.length);
       }
       return new TypeUseGenerator(this, token, declaration, name);
     } else if (declaration.isLocal) {
       if (constantContext != ConstantContext.none &&
           !declaration.isConst &&
           !member.isConstructor) {
-        deprecated_addCompileTimeError(
-            charOffset, "Not a constant expression.");
+        addCompileTimeError(
+            fasta.messageNotAConstantExpression, charOffset, token.length);
       }
       // An initializing formal parameter might be final without its
       // VariableDeclaration being final. See
@@ -1578,8 +1578,8 @@
           // semantics, such parameters introduces a new parameter with that
           // name that should be resolved here.
           !member.isConstructor) {
-        deprecated_addCompileTimeError(
-            charOffset, "Not a constant expression.");
+        addCompileTimeError(
+            fasta.messageNotAConstantExpression, charOffset, token.length);
       }
       Name n = new Name(name, library.library);
       Member getter;
@@ -1619,8 +1619,8 @@
         if (!(readTarget is Field && readTarget.isConst ||
             // Static tear-offs are also compile time constants.
             readTarget is Procedure)) {
-          deprecated_addCompileTimeError(
-              charOffset, "Not a constant expression.");
+          addCompileTimeError(
+              fasta.messageNotAConstantExpression, charOffset, token.length);
         }
       }
       return generator;
@@ -2278,8 +2278,10 @@
     DartType type = pop();
     Expression expression = popForValue();
     if (constantContext != ConstantContext.none) {
-      push(deprecated_buildCompileTimeError(
-          "Not a constant expression.", operator.charOffset));
+      push(buildCompileTimeError(
+          fasta.templateNotConstantExpression.withArguments('As expression'),
+          operator.charOffset,
+          operator.length));
     } else {
       push(forest.asExpression(expression, type, operator));
     }
@@ -2298,8 +2300,10 @@
           type, functionNestingLevel);
     }
     if (constantContext != ConstantContext.none) {
-      push(deprecated_buildCompileTimeError(
-          "Not a constant expression.", isOperator.charOffset));
+      push(buildCompileTimeError(
+          fasta.templateNotConstantExpression.withArguments('Is expression'),
+          isOperator.charOffset,
+          isOperator.length));
     } else {
       push(isExpression);
     }
@@ -2890,8 +2894,10 @@
     debugEvent("beginNewExpression");
     super.push(constantContext);
     if (constantContext != ConstantContext.none) {
-      deprecated_addCompileTimeError(
-          token.charOffset, "Not a constant expression.");
+      addCompileTimeError(
+          fasta.templateNotConstantExpression.withArguments('New expression'),
+          token.charOffset,
+          token.length);
     }
     constantContext = ConstantContext.none;
   }
@@ -3273,7 +3279,7 @@
       ..fileEndOffset = token.charOffset);
     if (constantContext != ConstantContext.none) {
       push(deprecated_buildCompileTimeError(
-          "Not a constant expression.", formals.charOffset));
+          null, formals.charOffset, fasta.messageNotAConstantExpression));
     } else {
       push(new FunctionExpressionJudgment(function)
         ..fileOffset = offsetForToken(beginToken));
@@ -4151,12 +4157,12 @@
   }
 
   @override
-  void deprecated_addCompileTimeError(int charOffset, String message,
-      {bool wasHandled: false}) {
+  void deprecated_addCompileTimeError(int charOffset, String error,
+      {fasta.Message message, bool wasHandled: false}) {
     // TODO(ahe): Consider setting [constantContext] to `ConstantContext.none`
     // to avoid a long list of errors.
     return library.addCompileTimeError(
-        fasta.templateUnspecified.withArguments(message),
+        message ?? fasta.templateUnspecified.withArguments(error),
         charOffset,
         noLength,
         uri,
diff --git a/pkg/front_end/lib/src/fasta/kernel/expression_generator.dart b/pkg/front_end/lib/src/fasta/kernel/expression_generator.dart
index 9409dc1..f624f3f 100644
--- a/pkg/front_end/lib/src/fasta/kernel/expression_generator.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/expression_generator.dart
@@ -16,6 +16,7 @@
         messageCantUsePrefixAsExpression,
         messageCantUsePrefixWithNullAware,
         messageInvalidInitializer,
+        messageNotAConstantExpression,
         templateCantUseDeferredPrefixAsConstant,
         templateDeferredTypeAnnotation,
         templateIntegerLiteralIsOutOfRange,
@@ -211,8 +212,8 @@
     } else {
       if (helper.constantContext != ConstantContext.none &&
           send.name != lengthName) {
-        helper.deprecated_addCompileTimeError(
-            offsetForToken(token), "Not a constant expression.");
+        helper.addCompileTimeError(
+            messageNotAConstantExpression, offsetForToken(token), token.length);
       }
       return PropertyAccessGenerator.make(helper, send.token, buildSimpleRead(),
           send.name, null, null, isNullAware);
@@ -944,7 +945,7 @@
   Expression handleAssignment(bool voidContext) {
     if (helper.constantContext != ConstantContext.none) {
       return helper.deprecated_buildCompileTimeError(
-          "Not a constant expression.", offsetForToken(token));
+          null, offsetForToken(token), messageNotAConstantExpression);
     }
     if (identical("=", assignmentOperator)) {
       return generator.buildAssignment(value, voidContext: voidContext);
diff --git a/pkg/front_end/lib/src/fasta/kernel/expression_generator_helper.dart b/pkg/front_end/lib/src/fasta/kernel/expression_generator_helper.dart
index a7b7d47..a9e37ce 100644
--- a/pkg/front_end/lib/src/fasta/kernel/expression_generator_helper.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/expression_generator_helper.dart
@@ -77,7 +77,8 @@
 
   Expression wrapInCompileTimeError(Expression expression, Message message);
 
-  Expression deprecated_buildCompileTimeError(String error, [int offset]);
+  Expression deprecated_buildCompileTimeError(String error,
+      [int offset, Message message]);
 
   Initializer buildInvalidInitializer(Expression expression, [int offset]);
 
@@ -144,6 +145,9 @@
   DartType validatedTypeVariableUse(
       TypeParameterType type, int offset, bool nonInstanceAccessIsError);
 
+  void addCompileTimeError(Message message, int charOffset, int length,
+      {List<LocatedMessage> context});
+
   void addProblem(Message message, int charOffset, int length);
 
   void addProblemErrorIfConst(Message message, int charOffset, int length);
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_expression_generator.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_expression_generator.dart
index 36aaf0f..6f72d90 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_expression_generator.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_expression_generator.dart
@@ -13,6 +13,7 @@
     show
         LocatedMessage,
         messageLoadLibraryTakesNoArguments,
+        messageNotAConstantExpression,
         messageSuperAsExpression,
         templateNotConstantExpression;
 
@@ -643,8 +644,8 @@
   @override
   Expression doInvocation(int offset, Arguments arguments) {
     if (helper.constantContext != ConstantContext.none) {
-      helper.deprecated_addCompileTimeError(
-          offset, "Not a constant expression.");
+      // TODO(brianwilkerson) Fix the length
+      helper.addCompileTimeError(messageNotAConstantExpression, offset, 1);
     }
     if (getter == null || isFieldOrGetter(getter)) {
       return helper.buildMethodInvocation(
diff --git a/pkg/front_end/messages.status b/pkg/front_end/messages.status
index 5d23994..a9a5a52 100644
--- a/pkg/front_end/messages.status
+++ b/pkg/front_end/messages.status
@@ -246,6 +246,7 @@
 NonAsciiIdentifier/expression: Fail
 NonInstanceTypeVariableUse/example: Fail
 NonPartOfDirectiveInPart/script1: Fail
+NotAConstantExpression/example: Fail
 NotAPrefixInTypeAnnotation/example: Fail
 NotAType/example: Fail
 NotAnLvalue/analyzerCode: Fail
diff --git a/pkg/front_end/messages.yaml b/pkg/front_end/messages.yaml
index ccacf893..81817dc 100644
--- a/pkg/front_end/messages.yaml
+++ b/pkg/front_end/messages.yaml
@@ -140,6 +140,12 @@
   analyzerCode: NOT_CONSTANT_EXPRESSION
   dart2jsCode: "*fatal*"
 
+NotAConstantExpression:
+  template: "Not a constant expression."
+  severity: ERROR
+  analyzerCode: NOT_CONSTANT_EXPRESSION
+  dart2jsCode: "*fatal*"
+
 NonAsciiIdentifier:
   template: "The non-ASCII character '#character' (#unicode) can't be used in identifiers, only in strings and comments."
   tip: "Try using an US-ASCII letter, a digit, '_' (an underscore), or '$' (a dollar sign)."