diff --git a/plugins/_collections.js b/plugins/_collections.js
index 3c16658..af03a45 100644
--- a/plugins/_collections.js
+++ b/plugins/_collections.js
@@ -1750,7 +1750,6 @@ export const elems = {
       'height',
       'preserveAspectRatio',
       'style',
-      'version',
       'viewBox',
       'width',
       'x',
@@ -1764,20 +1763,10 @@ export const elems = {
       height: '100%',
       preserveAspectRatio: 'xMidYMid meet',
       zoomAndPan: 'magnify',
-      version: '1.1',
       baseProfile: 'none',
       contentScriptType: 'application/ecmascript',
       contentStyleType: 'text/css',
     },
-    deprecated: {
-      safe: new Set(['version']),
-      unsafe: new Set([
-        'baseProfile',
-        'contentScriptType',
-        'contentStyleType',
-        'zoomAndPan',
-      ]),
-    },
     contentGroups: new Set([
       'animation',
       'descriptive',
diff --git a/plugins/removeUnknownsAndDefaults.js b/plugins/removeUnknownsAndDefaults.js
index bce3ea8..a2fe565 100644
--- a/plugins/removeUnknownsAndDefaults.js
+++ b/plugins/removeUnknownsAndDefaults.js
@@ -116,7 +116,10 @@ export const fn = (root, params, info) => {
     }
     // See if the element or any of its parents are used.
     while (true) {
-      if (element.attributes.id && usedIDs.has(element.attributes.id)) {
+      if (
+        element.attributes.id &&
+        usedIDs.has(element.attributes.id.toString())
+      ) {
         return true;
       }
       const parent = element.parentNode;
@@ -294,7 +297,7 @@ export const fn = (root, params, info) => {
           // (b) not inheritable, and a default value.
           const isDefault = isDefaultPropertyValue(
             name,
-            value,
+            value.toString(),
             attributesDefaults,
           );
           if (inheritableAttrs.has(name)) {
diff --git a/test/plugins/removeUnknownsAndDefaults.32.svg.txt b/test/plugins/removeUnknownsAndDefaults.32.svg.txt
new file mode 100644
index 0000000..7232ffa
--- /dev/null
+++ b/test/plugins/removeUnknownsAndDefaults.32.svg.txt
@@ -0,0 +1,13 @@
+Remove <svg> version attribute.
+
+===
+
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 30 30" version="1.0">
+  <rect width="20" height="26" style="fill:blue;fill-opacity:0.5"/>
+</svg>
+
+@@@
+
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 30 30">
+    <rect width="20" height="26" style="fill:blue;fill-opacity:0.5"/>
+</svg>