diff --git a/plugins/prefixIds.js b/plugins/prefixIds.js
index cf8efe30..d81fd0cc 100644
--- a/plugins/prefixIds.js
+++ b/plugins/prefixIds.js
@@ -5,7 +5,9 @@ exports.type = 'perItem';
 exports.active = false;
 
 exports.params = {
-    delim: '__'
+    delim: '__',
+    prefixIds: true,
+    prefixClassNames: true,
 };
 
 exports.description = 'prefix IDs';
@@ -173,8 +175,8 @@ exports.fn = function(node, opts, extra) {
         csstree.walk(cssAst, function(node) {
 
             // #ID, .class
-            if ((node.type === 'IdSelector' ||
-                 node.type === 'ClassSelector') &&
+            if (((opts.prefixIds        && node.type === 'IdSelector') ||
+                 (opts.prefixClassNames && node.type === 'ClassSelector')) &&
                  node.name) {
                 node.name = addPrefix(node.name);
                 return;
@@ -204,11 +206,21 @@ exports.fn = function(node, opts, extra) {
         return node;
     }
 
-    // ID
-    addPrefixToIdAttr(node.attrs.id);
 
-    // Class
-    addPrefixToClassAttr(node.attrs.class);
+    // Nodes
+
+    if(opts.prefixIds) {
+        // ID
+        addPrefixToIdAttr(node.attrs.id);
+    }
+
+    if(opts.prefixClassNames) {
+        // Class
+        addPrefixToClassAttr(node.attrs.class);
+    }
+
+
+    // References
 
     // href
     addPrefixToHrefAttr(node.attrs.href);
@@ -216,7 +228,7 @@ exports.fn = function(node, opts, extra) {
     // (xlink:)href (deprecated, must be still supported)
     addPrefixToHrefAttr(node.attrs['xlink:href']);
 
-    // referenceable properties
+    // (referenceable) properties
     for (var referencesProp of referencesProps) {
         addPrefixToUrlAttr(node.attrs[referencesProp]);
     }
diff --git a/test/plugins/prefixIds.07.svg b/test/plugins/prefixIds.07.svg
new file mode 100644
index 00000000..add8a8d1
--- /dev/null
+++ b/test/plugins/prefixIds.07.svg
@@ -0,0 +1,27 @@
+<svg width="120" height="120" xmlns="http://www.w3.org/2000/svg">
+    <style>
+        .test {
+            color: blue;
+        }
+        #test {
+            color: red;
+        }
+
+    </style>
+    <rect class="test" x="10" y="10" width="100" height="100"/>
+    <rect class="" id="test" x="10" y="10" width="100" height="100"/>
+</svg>
+
+@@@
+
+<svg width="120" height="120" xmlns="http://www.w3.org/2000/svg">
+    <style>
+        .prefixIds_07_svg__test{color:blue}#test{color:red}
+    </style>
+    <rect class="prefixIds_07_svg__test" x="10" y="10" width="100" height="100"/>
+    <rect class="" id="test" x="10" y="10" width="100" height="100"/>
+</svg>
+
+@@@
+
+{"prefixIds":false}
diff --git a/test/plugins/prefixIds.08.svg b/test/plugins/prefixIds.08.svg
new file mode 100644
index 00000000..1008b6cd
--- /dev/null
+++ b/test/plugins/prefixIds.08.svg
@@ -0,0 +1,27 @@
+<svg width="120" height="120" xmlns="http://www.w3.org/2000/svg">
+    <style>
+        .test {
+            color: blue;
+        }
+        #test {
+            color: red;
+        }
+
+    </style>
+    <rect class="test" x="10" y="10" width="100" height="100"/>
+    <rect class="" id="test" x="10" y="10" width="100" height="100"/>
+</svg>
+
+@@@
+
+<svg width="120" height="120" xmlns="http://www.w3.org/2000/svg">
+    <style>
+        .test{color:blue}#prefixIds_08_svg__test{color:red}
+    </style>
+    <rect class="test" x="10" y="10" width="100" height="100"/>
+    <rect class="" id="prefixIds_08_svg__test" x="10" y="10" width="100" height="100"/>
+</svg>
+
+@@@
+
+{"prefixClassNames":false}
diff --git a/test/plugins/prefixIds.09.svg b/test/plugins/prefixIds.09.svg
new file mode 100644
index 00000000..5d6d088a
--- /dev/null
+++ b/test/plugins/prefixIds.09.svg
@@ -0,0 +1,27 @@
+<svg width="120" height="120" xmlns="http://www.w3.org/2000/svg">
+    <style>
+        .test {
+            color: blue;
+        }
+        #test {
+            color: red;
+        }
+
+    </style>
+    <rect class="test" x="10" y="10" width="100" height="100"/>
+    <rect class="" id="test" x="10" y="10" width="100" height="100"/>
+</svg>
+
+@@@
+
+<svg width="120" height="120" xmlns="http://www.w3.org/2000/svg">
+    <style>
+        .test{color:blue}#test{color:red}
+    </style>
+    <rect class="test" x="10" y="10" width="100" height="100"/>
+    <rect class="" id="test" x="10" y="10" width="100" height="100"/>
+</svg>
+
+@@@
+
+{"prefixIds":false,"prefixClassNames":false}