diff --git a/lib/lexer.js b/lib/lexer.js
index be247ae5..1d850d05 100644
--- a/lib/lexer.js
+++ b/lib/lexer.js
@@ -252,7 +252,7 @@
         i += 1;
       }
       if (levels.length) {
-        throw new Error("SyntaxError: Unterminated " + (delimited[levels.pop()][0]) + " starting on line " + this.line);
+        throw new Error("SyntaxError: Unterminated " + (levels.pop()[0]) + " starting on line " + (this.line + 1));
       }
       if (i === 0) {
         return false;
@@ -441,12 +441,12 @@
     // Error for when you try to use a forbidden word in JavaScript as
     // an identifier.
     Lexer.prototype.identifier_error = function identifier_error(word) {
-      throw new Error("SyntaxError: Reserved word \"" + word + "\" on line " + this.line);
+      throw new Error("SyntaxError: Reserved word \"" + word + "\" on line " + (this.line + 1));
     };
     // Error for when you try to assign to a reserved word in JavaScript,
     // like "function" or "default".
     Lexer.prototype.assignment_error = function assignment_error() {
-      throw new Error("SyntaxError: Reserved word \"" + (this.value()) + "\" on line " + this.line + " can't be assigned");
+      throw new Error("SyntaxError: Reserved word \"" + (this.value()) + "\" on line " + (this.line + 1) + " can't be assigned");
     };
     // Expand variables and expressions inside double-quoted strings using
     // [ECMA Harmony's interpolation syntax](http://wiki.ecmascript.org/doku.php?id=strawman:string_interpolation).
diff --git a/lib/rewriter.js b/lib/rewriter.js
index 73231cea..dea82090 100644
--- a/lib/rewriter.js
+++ b/lib/rewriter.js
@@ -292,7 +292,7 @@
               levels[open] -= 1;
             }
             if (levels[open] < 0) {
-              throw new Error("too many " + (token[1]));
+              throw new Error("too many " + (token[1]) + " on line " + (token[2] + 1));
             }
           }
           return 1;
diff --git a/src/lexer.coffee b/src/lexer.coffee
index fef95e85..fb6e4fb2 100644
--- a/src/lexer.coffee
+++ b/src/lexer.coffee
@@ -220,7 +220,7 @@ exports.Lexer: class Lexer
           break
       break unless levels.length
       i += 1
-    throw new Error "SyntaxError: Unterminated ${delimited[levels.pop()][0]} starting on line $@line" if levels.length
+    throw new Error "SyntaxError: Unterminated ${levels.pop()[0]} starting on line ${@line + 1}" if levels.length
     return false if i is 0
     return @chunk.substring(0, i)
 
@@ -362,12 +362,12 @@ exports.Lexer: class Lexer
   # Error for when you try to use a forbidden word in JavaScript as
   # an identifier.
   identifier_error: (word) ->
-    throw new Error "SyntaxError: Reserved word \"$word\" on line $@line"
+    throw new Error "SyntaxError: Reserved word \"$word\" on line ${@line + 1}"
 
   # Error for when you try to assign to a reserved word in JavaScript,
   # like "function" or "default".
   assignment_error: ->
-    throw new Error "SyntaxError: Reserved word \"${@value()}\" on line $@line can't be assigned"
+    throw new Error "SyntaxError: Reserved word \"${@value()}\" on line ${@line + 1} can't be assigned"
 
   # Expand variables and expressions inside double-quoted strings using
   # [ECMA Harmony's interpolation syntax](http://wiki.ecmascript.org/doku.php?id=strawman:string_interpolation).
diff --git a/src/rewriter.coffee b/src/rewriter.coffee
index b7b04a80..df932922 100644
--- a/src/rewriter.coffee
+++ b/src/rewriter.coffee
@@ -193,7 +193,7 @@ exports.Rewriter: class Rewriter
         levels[open] ||= 0
         levels[open] += 1 if token[0] is open
         levels[open] -= 1 if token[0] is close
-        throw new Error("too many ${token[1]}") if levels[open] < 0
+        throw new Error("too many ${token[1]} on line ${token[2] + 1}") if levels[open] < 0
       return 1
     unclosed: key for key, value of levels when value > 0
     throw new Error("unclosed ${unclosed[0]}") if unclosed.length