diff --git a/parse.js b/parse.js
index 301515c..795ec7b 100755
--- a/parse.js
+++ b/parse.js
@@ -1,5 +1,4 @@
 #! /usr/bin/node
-
 var fs = require("fs");
 var typ = require("./representation.js");
 var $ = require("./tools.js");
@@ -401,25 +400,34 @@ function parseIf(tokens) {
 	}
 	else {
 		var ifC = parse(tokens);
-		if (!fst(tokens) || fst(tokens)[0] !== "thenexp")
+		if (!fst(tokens) || fst(tokens)[0] !== "thenexp") {
 			throw error.JSyntaxError(fst(tokens)[3],
                                fst(tokens)[2],
                                "if ``exp'' must be folowed by ``then'' exp, not "+snd(tokens)[0]);
+    }
 		else {
 			tokens.pop();
 			var thenC = parse(tokens);
 
 			if (fst(tokens) && fst(tokens)[0] === "elsexp") {
 				tokens.pop();
+        if (_.size(tokens) < 1) {
+          throw error.JSyntaxError(linenum,
+                                   charnum,
+                                   "Unexpected end of source");
+        }
+      else {
 				var elseC = parse(tokens);
 				return new typ.If(ifC, thenC, elseC);
-
-			}
-			else {
-				return new typ.If(ifC, thenC);
-			}
-		}
-	}
+        }
+      }
+      else {
+        throw error.JSyntaxError(linenum,
+                                 charnum,
+                                 "If expression must include an else variant");
+      }
+    }
+  }
 }
 
 
diff --git a/representation.js b/representation.js
index ea4ba57..646429b 100644
--- a/representation.js
+++ b/representation.js
@@ -157,8 +157,7 @@ function DefFunc(ident, params, body) {
 function If(condition, thenexp, elseexp) {
 	this.condition = condition;
 	this.thenexp = thenexp;
-  if (elseexp)
-		this.elseexp = elseexp;
+	this.elseexp = elseexp;
 	this.exprType = "If";
 	return this;
 }
diff --git a/tokenize.js b/tokenize.js
index 47ffcc4..99b2be3 100755
--- a/tokenize.js
+++ b/tokenize.js
@@ -215,7 +215,7 @@ function tokenize(tokstream, matchop) {
       case 45: // '-'
         lambda = peek(tokstream, "arrow", "->");
         if (lambda) {
-          tokens.push(lambda);
+          tokens.push($.extend(lambda, [charnum, linenum]));
           tokstream = tokstream.substr(2);
           break;
         }
@@ -242,7 +242,7 @@ function tokenize(tokstream, matchop) {
       case 116: // 't'
         result = tokenizeT(tokstream);
         if (result) {
-          tokens.push(result);
+          tokens.push($.extend(result, [charnum, linenum]));
           tokstream = tokstream.substr(4); // 4 = length of either token
           break;
         }
@@ -250,13 +250,13 @@ function tokenize(tokstream, matchop) {
       case 105: // 'i'
         var ifexp = peek(tokstream, "ifexp", "if");
         if (ifexp) {
-          tokens.push(ifexp);
+          tokens.push($.extend(ifexp, [linenum, charnum]));
           tokstream = tokstream.substr(2);
           break;
         }
         var inkeyword = peek(tokstream, "in", "in ");
         if (inkeyword) {
-          tokens.push(inkeyword);
+          tokens.push($.extend(inkeyword, [charnum, linenum]));
           tokstream = tokstream.substr(3);
           break;
         }
@@ -279,7 +279,7 @@ function tokenize(tokstream, matchop) {
       case 101: // e
         result = peek(tokstream, "elsexp", "else");
         if (result) {
-          tokens.push(result);
+          tokens.push($.extend(result, [charnum, linenum]));
           tokstream = tokstream.substr(4);
           break;
         }
@@ -287,7 +287,7 @@ function tokenize(tokstream, matchop) {
       case 102: // f
         result = peek(tokstream, "falselit", "false");
         if (result) {
-          tokens.push(result);
+          tokens.push($.extend(result, [charnum, linenum]));
           tokstream = tokstream.substr(5);
           break;
         }
@@ -295,13 +295,13 @@ function tokenize(tokstream, matchop) {
       case 108: // l
         lambda = peek(tokstream, "lambda", "lambda");
         if (lambda) {
-          tokens.push(lambda);
+          tokens.push($.extend(lambda, [linenum, charnum]));
           tokstream = tokstream.substr(6);
           break;
         }
         var letexp = peek(tokstream, "let", "let");
         if (letexp) {
-          tokens.push(letexp);
+          tokens.push($.extend(letexp, [charnum, linenum]));
           tokstream = tokstream.substr(3);
           break;
         }