diff --git a/src/bg/RequestUtil.js b/src/bg/RequestUtil.js
index 5a52975..629f270 100644
--- a/src/bg/RequestUtil.js
+++ b/src/bg/RequestUtil.js
@@ -47,8 +47,8 @@
 
   var RequestUtil = {
 
-    getContentMetaData(request) {
-      return request.content || (request.content = new ContentMetaData(request));
+    getResponseMetaData(request) {
+      return request.response || (request.response = new ResponseMetaData(request));
     },
 
     async executeOnStart(request, details) {
@@ -63,12 +63,14 @@
           return;
         }
       }
-      let content = this.getContentMetaData(request);
-      if (content.disposition) {
-        debug("Skipping execute on start of %s %o", url, content);
+      
+      let response = this.getResponseMetaData(request);
+      let {contentType, contentDisposition} = response;
+      if (contentDisposition) {
+        debug("Skipping execute on start of %s %o", url, response);
         return;
       }
-      debug("Injecting script on start in %s (%o)", url, content);
+      debug("Injecting script on start in %s (%o)", url, response);
 
       let scripts = pendingRequests.get(requestId);
       let scriptKey = JSON.stringify(details);
@@ -80,12 +82,12 @@
         return;
       }
 
-      if (xmlFeedOrImage.test(content.type) && !/\/svg\b/i.test(content.type)) return;
+      if (xmlFeedOrImage.test(contentType) && !/\/svg\b/i.test(contentType)) return;
       if (typeof brokenXMLOnLoad === "undefined") {
         brokenXMLOnLoad = await (async () => parseInt((await browser.runtime.getBrowserInfo()).version) < 61)();
       }
 
-      let mustCheckFeed = brokenXMLOnLoad && frameId === 0 && rawXml.test(content.type);
+      let mustCheckFeed = brokenXMLOnLoad && frameId === 0 && rawXml.test(contentType);
       debug("mustCheckFeed = %s, brokenXMLOnLoad = %s", mustCheckFeed, brokenXMLOnLoad);
       let filter = browser.webRequest.filterResponseData(requestId);
       let buffer = [];
diff --git a/src/lib/ContentMetaData.js b/src/lib/ContentMetaData.js
deleted file mode 100644
index 002a212..0000000
--- a/src/lib/ContentMetaData.js
+++ /dev/null
@@ -1,31 +0,0 @@
-class ContentMetaData {
-  constructor(request, defaultCharset = "utf-8") {
-    this.defaultCharset = defaultCharset;
-    let {responseHeaders} = request;
-    for (let h of responseHeaders) {
-      if (/^\s*Content-(Type|Disposition)\s*$/i.test(h.name)) {
-        this[RegExp.$1.toLowerCase()] = h.value;
-      }
-    }
-  }
-
-  get charset() {
-    let charset = this.defaultCharset;
-    if (this.type) {
-      let m = this.type.match(/;\s*charset\s*=\s*(\S+)/);
-      if (m) {
-        charset = m[1];
-      }
-    }
-    Object.defineProperty(this, "charset", { value: charset, writable: false, configurable: true });
-    return charset;
-  }
-
-  createDecoder() {
-    try {
-      return new TextDecoder(this.charset);
-    } catch (e) {
-      return new TextDecoder(this.defaultCharset);
-    }
-  }
-};
diff --git a/src/lib/ResponseMetaData.js b/src/lib/ResponseMetaData.js
new file mode 100644
index 0000000..17e1608
--- /dev/null
+++ b/src/lib/ResponseMetaData.js
@@ -0,0 +1,54 @@
+class ResponseMetaData {
+  constructor(request) {
+    let {responseHeaders} = request;
+    this.headers = {};
+    this.contentType = this.contentDisposition = null;
+    for (let h of responseHeaders) {
+      if (/^\s*Content-(Type|Disposition)\s*$/i.test(h.name)) {
+        let propertyName = RegExp.$1;
+        propertyName = `content${propertyName.charAt(0).toUpperCase()}${propertyName.substring(1).toLowerCase()}`;
+        this[propertyName] = h.value;
+        this.headers[propertyName] = h;
+      }
+    }
+    this.forcedUTF8 = false;
+  }
+
+  get charset() {
+    let charset = "";
+    if (this.contentType) {
+      let m = this.contentType.match(/;\s*charset\s*=\s*(\S+)/);
+      if (m) {
+        charset = m[1];
+      }
+    }
+    Object.defineProperty(this, "charset", { value: charset, writable: false, configurable: true });
+    return charset;
+  }
+
+  get isUTF8() {
+    return /^utf-8$/i.test(this.charset);
+  }
+
+  forceUTF8() {
+    if (!(this.forcedUTF8 || this.isUTF8)) {
+      let h = this.headers.contentType;
+      if (h) {
+        h.value = h.value.replace(/;\s*charset\s*=.*|$/, "; charset=utf8");
+        this.forcedUTF8 = true;
+      } // if the header doesn't exist the browser should default to UTF-8 anyway
+    }
+    return this.forcedUTF8;
+  }
+
+  createDecoder() {
+    if (this.charset) {
+      try {
+        return new TextDecoder(this.charset);
+      } catch (e) {
+        console.error(e);
+      }
+    }
+    return new TextDecoder("utf-8");
+  }
+};
diff --git a/src/manifest.json b/src/manifest.json
index 9cb967c..acb237f 100644
--- a/src/manifest.json
+++ b/src/manifest.json
@@ -39,7 +39,7 @@
       "lib/include.js",
       "lib/punycode.js",
       "lib/tld.js",
-      "lib/ContentMetaData.js",
+      "lib/ResponseMetaData.js",
       "common/Policy.js",
       "common/locale.js",
       "common/Entities.js",