diff --git a/src/definitions/modules/dimmer.js b/src/definitions/modules/dimmer.js
index 232854e12..f622e925a 100755
--- a/src/definitions/modules/dimmer.js
+++ b/src/definitions/modules/dimmer.js
@@ -92,10 +92,6 @@ $.fn.dimmer = function(parameters) {
 
           module.bind.events();
           module.set.dimmable();
-          if(!settings.useFlex) {
-            module.debug('Absolutely positioned flex not supported. Using legacy positioning.');
-            module.set.legacy();
-          }
           module.instantiate();
         },
 
@@ -247,6 +243,14 @@ $.fn.dimmer = function(parameters) {
               : function(){}
             ;
             if(settings.useCSS && $.fn.transition !== undefined && $dimmer.transition('is supported')) {
+              if(settings.useFlex) {
+                module.debug('Using flex dimmer');
+                module.remove.legacy();
+              }
+              else {
+                module.debug('Using legacy non-flex dimmer');
+                module.set.legacy();
+              }
               if(settings.opacity !== 'auto') {
                 module.set.opacity();
               }
@@ -455,6 +459,9 @@ $.fn.dimmer = function(parameters) {
               .removeClass(className.active)
             ;
           },
+          legacy: function() {
+            $dimmer.removeClass(className.legacy);
+          },
           dimmed: function() {
             $dimmable.removeClass(className.dimmed);
           },
diff --git a/src/definitions/modules/dimmer.less b/src/definitions/modules/dimmer.less
index 24faa4680..fb0ce54c5 100755
--- a/src/definitions/modules/dimmer.less
+++ b/src/definitions/modules/dimmer.less
@@ -125,12 +125,6 @@
   display: block;
 }
 
-/* Resort to normal positioning */
-.ui.legacy.page.dimmer > .ui.modal {
-  top: 50%;
-  left: 50%;
-}
-
 /*--------------
     Alignment
 ---------------*/
diff --git a/src/definitions/modules/modal.js b/src/definitions/modules/modal.js
index b0432a1a7..f281a3b08 100755
--- a/src/definitions/modules/modal.js
+++ b/src/definitions/modules/modal.js
@@ -107,7 +107,6 @@ $.fn.modal = function(parameters) {
           dimmer: function() {
             var
               defaultSettings = {
-                useFlex    : module.can.useFlex(),
                 debug      : settings.debug,
                 variation  : settings.centered
                   ? false
@@ -133,7 +132,7 @@ $.fn.modal = function(parameters) {
             $dimmer = $dimmable.dimmer('get dimmer');
           },
           id: function() {
-            id = (Math.random().toString(16) + '000000000').substr(2,8);
+            id = (Math.random().toString(16) + '000000000').substr(2, 8);
             elementEventNamespace = '.' + id;
             module.verbose('Creating unique id for element', id);
           }
@@ -216,7 +215,7 @@ $.fn.modal = function(parameters) {
 
         get: {
           id: function() {
-            return (Math.random().toString(16) + '000000000').substr(2,8);
+            return (Math.random().toString(16) + '000000000').substr(2, 8);
           }
         },
 
@@ -326,11 +325,15 @@ $.fn.modal = function(parameters) {
             : function(){}
           ;
           if( module.is.animating() || !module.is.active() ) {
-
             module.showDimmer();
             module.cacheSizes();
-            if(!module.can.useFlex()) {
+            if(module.can.useFlex()) {
+              module.remove.legacy();
+            }
+            else {
+              module.set.legacy();
               module.set.modalOffset();
+              module.debug('Using non-flex legacy modal positioning.');
             }
             module.set.screenHeight();
             module.set.type();
@@ -520,6 +523,9 @@ $.fn.modal = function(parameters) {
           active: function() {
             $module.removeClass(className.active);
           },
+          legacy: function() {
+            $module.removeClass(className.legacy);
+          },
           clickaway: function() {
             $dimmer
               .off('click' + elementEventNamespace)
@@ -618,7 +624,7 @@ $.fn.modal = function(parameters) {
           },
           modernBrowser: function() {
             // appName for IE11 reports 'Netscape' can no longer use
-            return !(window.ActiveXObject || "ActiveXObject" in window);
+            return !(window.ActiveXObject || 'ActiveXObject' in window);
           }
         },
 
@@ -650,10 +656,10 @@ $.fn.modal = function(parameters) {
                 debug      : settings.debug,
                 dimmerName : 'modals',
                 closable   : 'auto',
+                useFlex    : module.can.useFlex(),
                 variation  : settings.centered
                   ? false
-                  : 'top aligned'
-                ,
+                  : 'top aligned',
                 duration   : {
                   show     : settings.duration,
                   hide     : settings.duration
@@ -710,6 +716,9 @@ $.fn.modal = function(parameters) {
             $dimmable.addClass(className.scrolling);
             $module.addClass(className.scrolling);
           },
+          legacy: function() {
+            $module.addClass(className.legacy);
+          },
           type: function() {
             if(module.can.fit()) {
               module.verbose('Modal fits on screen');
@@ -986,6 +995,7 @@ $.fn.modal.settings = {
     animating  : 'animating',
     blurring   : 'blurring',
     inverted   : 'inverted',
+    legacy     : 'legacy',
     loading    : 'loading',
     scrolling  : 'scrolling',
     undetached : 'undetached'
diff --git a/src/definitions/modules/modal.less b/src/definitions/modules/modal.less
index 0b59b5d61..03e12b954 100755
--- a/src/definitions/modules/modal.less
+++ b/src/definitions/modules/modal.less
@@ -310,6 +310,13 @@
   color: @basicInvertedModalHeaderColor;
 }
 
+/* Resort to margin positioning if legacy */
+.ui.legacy.modal,
+.ui.legacy.page.dimmer > .ui.modal {
+  top: 50%;
+  left: 50%;
+}
+
 /* Tablet and Mobile */
 @media only screen and (max-width : @largestTabletScreen) {
   .ui.basic.modal > .close {