diff --git a/lib/coffee-script/lexer.js b/lib/coffee-script/lexer.js
index 8c560c36..8d46f338 100644
--- a/lib/coffee-script/lexer.js
+++ b/lib/coffee-script/lexer.js
@@ -112,8 +112,8 @@
       var binaryLiteral, lexedLength, match, number, octalLiteral;
       if (!(match = NUMBER.exec(this.chunk))) return 0;
       number = match[0];
-      if (/[E]/.test(number)) {
-        this.error("exponential notation must be indicated with a lowercase 'e'");
+      if (/E/.test(number)) {
+        this.error("exponential notation '" + number + "' must be indicated with a lowercase 'e'");
       } else if (/[BOX]/.test(number)) {
         this.error("radix prefixes must be lowercase '" + number + "'");
       } else if (/^0[89]/.test(number)) {
diff --git a/src/lexer.coffee b/src/lexer.coffee
index 8544b8f1..55a4821f 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -133,8 +133,8 @@ exports.Lexer = class Lexer
   numberToken: ->
     return 0 unless match = NUMBER.exec @chunk
     number = match[0]
-    if /[E]/.test number
-      @error "exponential notation must be indicated with a lowercase 'e'"
+    if /E/.test number
+      @error "exponential notation '#{number}' must be indicated with a lowercase 'e'"
     else if /[BOX]/.test number
       @error "radix prefixes must be lowercase '#{number}'"
     else if /^0[89]/.test number