diff --git a/lib/markdownlint.js b/lib/markdownlint.js
index 27aa806b..52a7defa 100644
--- a/lib/markdownlint.js
+++ b/lib/markdownlint.js
@@ -8,42 +8,38 @@ var md = require("markdown-it")({ "html": true });
 var rules = require("./rules");
 var shared = require("./shared");
 
-// Mappings from rule to description and name/tag to rules
-var allRuleNames = [];
-var ruleNameToRule = {};
-var idUpperToRuleNames = {};
+// Mapping from rule names/tags to canonical rule name
+var aliasToRuleNames = {};
 // var tagToRuleNames = {};
 rules.forEach(function forRule(rule) {
-  var ruleName = rule.names[0];
-  var ruleAliases = rule.names.slice(1);
-  allRuleNames.push(ruleName);
-  ruleNameToRule[ruleName] = rule;
+  var ruleName = rule.names[0].toUpperCase();
   // The following is useful for updating README.md
   // console.log(
   //   "* **[" + ruleName + "](doc/Rules.md#" + ruleName.toLowerCase() +
-  //    ")** *" + ruleAliases.join(", ") + "* - " + rule.description);
+  //    ")** *" + rule.names.slice(1).join(", ") + "* - " + rule.description);
+  rule.names.forEach(function forName(name) {
+    var nameUpper = name.toUpperCase();
+    aliasToRuleNames[nameUpper] = [ ruleName ];
+  });
   rule.tags.forEach(function forTag(tag) {
     var tagUpper = tag.toUpperCase();
-    var ruleNames = idUpperToRuleNames[tagUpper] || [];
+    var ruleNames = aliasToRuleNames[tagUpper] || [];
     ruleNames.push(ruleName);
-    idUpperToRuleNames[tagUpper] = ruleNames;
+    aliasToRuleNames[tagUpper] = ruleNames;
     // tagToRuleNames[tag] = ruleName;
   });
-  ruleAliases.forEach(function forAlias(alias) {
-    var aliasUpper = alias.toUpperCase();
-    idUpperToRuleNames[aliasUpper] = [ ruleName ];
-  });
 });
 // The following is useful for updating README.md
 // Object.keys(tagToRuleNames).sort().forEach(function forTag(tag) {
 //   console.log("* **" + tag + "** - " +
-//     idUpperToRuleNames[tag.toUpperCase()].join(", "));
+//     aliasToRuleNames[tag.toUpperCase()].join(", "));
 // });
 
 // Class for results with toString for pretty display
 function Results() {}
 Results.prototype.toString = function resultsToString(useAlias) {
   var that = this;
+  var ruleNameToRule = null;
   var results = [];
   Object.keys(that).forEach(function forFile(file) {
     var fileResults = that[file];
@@ -65,6 +61,13 @@ Results.prototype.toString = function resultsToString(useAlias) {
             ""));
       });
     } else {
+      if (!ruleNameToRule) {
+        ruleNameToRule = {};
+        rules.forEach(function forRule(rule) {
+          var ruleName = rule.names[0].toUpperCase();
+          ruleNameToRule[ruleName] = rule;
+        });
+      }
       Object.keys(fileResults).forEach(function forRule(ruleName) {
         var rule = ruleNameToRule[ruleName];
         var ruleResults = fileResults[ruleName];
@@ -163,7 +166,7 @@ function lintContent(
   var ruleDefault = (defaultKey.length === 0) || !!config[defaultKey[0]];
   var mergedRules = {};
   rules.forEach(function forRule(rule) {
-    var ruleName = rule.names[0];
+    var ruleName = rule.names[0].toUpperCase();
     mergedRules[ruleName] = ruleDefault;
   });
   Object.keys(config).forEach(function forKey(key) {
@@ -176,18 +179,16 @@ function lintContent(
       value = false;
     }
     var keyUpper = key.toUpperCase();
-    if (ruleNameToRule[keyUpper]) {
-      mergedRules[keyUpper] = value;
-    } else if (idUpperToRuleNames[keyUpper]) {
-      idUpperToRuleNames[keyUpper].forEach(function forRule(ruleName) {
-        mergedRules[ruleName] = value;
-      });
-    }
+    (aliasToRuleNames[keyUpper] || []).forEach(function forRule(ruleName) {
+      mergedRules[ruleName] = value;
+    });
   });
   // Create mapping of enabled rules per line
   var enabledRules = {};
+  var allRuleNames = [];
   rules.forEach(function forRule(rule) {
-    var ruleName = rule.names[0];
+    var ruleName = rule.names[0].toUpperCase();
+    allRuleNames.push(ruleName);
     enabledRules[ruleName] = !!mergedRules[ruleName];
   });
   function forMatch(match) {
@@ -196,13 +197,9 @@ function lintContent(
       match[2].trim().toUpperCase().split(/\s+/) :
       allRuleNames;
     items.forEach(function forItem(nameUpper) {
-      if (ruleNameToRule[nameUpper]) {
-        enabledRules[nameUpper] = enabled;
-      } else if (idUpperToRuleNames[nameUpper]) {
-        idUpperToRuleNames[nameUpper].forEach(function forRule(ruleName) {
-          enabledRules[ruleName] = enabled;
-        });
-      }
+      (aliasToRuleNames[nameUpper] || []).forEach(function forRule(ruleName) {
+        enabledRules[ruleName] = enabled;
+      });
     });
   }
   var enabledRulesPerLineNumber = new Array(1 + frontMatterLines.length);
@@ -230,7 +227,7 @@ function lintContent(
   var result = (resultVersion === 0) ? {} : [];
   rules.forEach(function forRule(rule) {
     // Configure rule
-    var ruleName = rule.names[0];
+    var ruleName = rule.names[0].toUpperCase();
     params.config = mergedRules[ruleName];
     var errors = [];
     function onError(errorInfo) {