diff --git a/src/js/messaging.js b/src/js/messaging.js
index 4eefbeb9c..5855baf9f 100644
--- a/src/js/messaging.js
+++ b/src/js/messaging.js
@@ -517,6 +517,7 @@ var onMessage = function(request, sender, callback) {
         // already been injected.
         if (
             µb.canFilterResponseBody === false ||
+            µb.textEncode === undefined ||
             µb.textEncode.normalizeCharset(request.charset) === undefined
         ) {
             response.scriptlets = µb.scriptletFilteringEngine.retrieve(request);
diff --git a/src/js/text-encode.js b/src/js/text-encode.js
index 7b2823aa3..93ac0ff62 100644
--- a/src/js/text-encode.js
+++ b/src/js/text-encode.js
@@ -25,16 +25,40 @@
 
 µBlock.textEncode = (function() {
 
+    if ( µBlock.canFilterResponseBody !== true ) { return; }
+
+    // charset aliases extracted from:
+    // https://github.com/inexorabletash/text-encoding/blob/b4e5bc26e26e51f56e3daa9f13138c79f49d3c34/lib/encoding.js#L342
     var normalizedCharset = new Map([
         [ 'utf8', 'utf-8' ],
         [ 'unicode-1-1-utf-8', 'utf-8' ],
         [ 'utf-8', 'utf-8' ],
+
         [ 'windows-1250', 'windows-1250' ],
         [ 'cp1250', 'windows-1250' ],
         [ 'x-cp1250', 'windows-1250' ],
+
         [ 'windows-1251', 'windows-1251' ],
         [ 'cp1251', 'windows-1251' ],
         [ 'x-cp1251', 'windows-1251' ],
+
+        [ 'windows-1252', 'windows-1252' ],
+        [ 'ansi_x3.4-1968', 'windows-1252' ],
+        [ 'ascii', 'windows-1252' ],
+        [ 'cp1252', 'windows-1252' ],
+        [ 'cp819', 'windows-1252' ],
+        [ 'csisolatin1', 'windows-1252' ],
+        [ 'ibm819', 'windows-1252' ],
+        [ 'iso-8859-1', 'windows-1252' ],
+        [ 'iso-ir-100', 'windows-1252' ],
+        [ 'iso8859-1', 'windows-1252' ],
+        [ 'iso88591', 'windows-1252' ],
+        [ 'iso_8859-1', 'windows-1252' ],
+        [ 'iso_8859-1:1987', 'windows-1252' ],
+        [ 'l1', 'windows-1252' ],
+        [ 'latin1', 'windows-1252' ],
+        [ 'us-ascii', 'windows-1252' ],
+        [ 'x-cp1252', 'windows-1252' ],
     ]);
 
     // http://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/CP1250.TXT
@@ -77,7 +101,17 @@
         /* 0x0478 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         /* 0x0480 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
         /* 0x0488 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
-        /* 0x0490 */ 0xA5, 0xB4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        /* 0x0490 */ 0xA5, 0xB4, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+    ]);
+
+    // https://www.unicode.org/Public/MAPPINGS/VENDORS/MICSFT/WINDOWS/CP1252.TXT
+    var cp1252_range0 = new Uint8Array([
+        /* 0x0150 */ 0x00, 0x00, 0x8C, 0x9C, 0x00, 0x00, 0x00, 0x00,
+        /* 0x0158 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        /* 0x0160 */ 0x8A, 0x9A, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        /* 0x0168 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        /* 0x0170 */ 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+        /* 0x0178 */ 0x9F, 0x00, 0x00, 0x00, 0x00, 0x8E, 0x9E, 0x00
     ]);
 
     var cp125x_range0 = new Uint8Array([
@@ -171,6 +205,47 @@
                 }
             }
             return buf.slice(0, o);
+        },
+        'windows-1252': function(buf) {
+            var i = 0, n = buf.byteLength, o = 0, c;
+            while ( i < n ) {
+                c = buf[i++];
+                if ( c < 0x80 ) {
+                    buf[o++] = c;
+                } else {
+                    if ( (c & 0xE0) === 0xC0 ) {
+                        c  = (c        & 0x1F) << 6;
+                        c |= (buf[i++] & 0x3F);
+                    } else if ( (c & 0xF0) === 0xE0 ) {
+                        c  = (c        & 0x0F) << 12;
+                        c |= (buf[i++] & 0x3F) << 6;
+                        c |= (buf[i++] & 0x3F);
+                    } else if ( (c & 0xF8) === 0xF0 ) {
+                        c  = (c        & 0x07) << 18;
+                        c |= (buf[i++] & 0x3F) << 12;
+                        c |= (buf[i++] & 0x3F) << 6;
+                        c |= (buf[i++] & 0x3F);
+                    }
+                    if ( c < 0x100 ) {
+                        buf[o++] = c;
+                    } else if ( c >= 0x150 && c < 0x180 ) {
+                        buf[o++] = cp1252_range0[c - 0x150];
+                    } else if ( c >= 0x2010 && c < 0x2040 ) {
+                        buf[o++] = cp125x_range0[c - 0x2010];
+                    } else if ( c === 0x192 ) {
+                        buf[o++] = 0x83;
+                    } else if ( c === 0x2C6 ) {
+                        buf[o++] = 0x88;
+                    } else if ( c === 0x2DC ) {
+                        buf[o++] = 0x98;
+                    } else if ( c === 0x20AC ) {
+                        buf[o++] = 0x80;
+                    } else if ( c === 0x2122 ) {
+                        buf[o++] = 0x99;
+                    }
+                }
+            }
+            return buf.slice(0, o);
         }
     };
 
diff --git a/src/js/traffic.js b/src/js/traffic.js
index fe6c59863..9a7dbf97b 100644
--- a/src/js/traffic.js
+++ b/src/js/traffic.js
@@ -577,7 +577,7 @@ var filterDocument = (function() {
     var µb = µBlock,
         filterers = new Map(),
         domParser, xmlSerializer,
-        textDecoderCharset, textDecoder, textEncoder;
+        utf8TextDecoder, textDecoder, textEncoder;
 
     var reContentTypeDocument = /^(?:text\/html|application\/xhtml+xml)/i,
         reContentTypeCharset = /charset=['"]?([^'" ]+)/i;
@@ -737,29 +737,17 @@ var filterDocument = (function() {
             textEncoder = new TextEncoder();
         }
 
-        // In case of unknown charset, assume utf-8.
-        if (
-            filterer.charset === undefined && textDecoderCharset !== 'utf-8' ||
-            filterer.charset !== undefined && filterer.charset !== textDecoderCharset
-        ) {
-            textDecoder = undefined;
-        }
-        if ( textDecoder === undefined ) {
-            try {
-                textDecoder = new TextDecoder(filterer.charset);
-                textDecoderCharset = filterer.charset || 'utf-8';
-            } catch(ex) {
-                textDecoder = new TextDecoder();
-                textDecoderCharset = 'utf-8';
-            }
-        }
-
-        var doc = domParser.parseFromString(
-            textDecoder.decode(filterer.buffer),
-            'text/html'
-        );
+        var doc;
 
+        // If stream encoding is still unknnown, try to extract from document.
         if ( filterer.charset === undefined ) {
+            if ( utf8TextDecoder === undefined ) {
+                utf8TextDecoder = new TextDecoder();
+            }
+            doc = domParser.parseFromString(
+                utf8TextDecoder.decode(filterer.buffer.slice(0, 1024)),
+                'text/html'
+            );
             filterer.charset = µb.textEncode.normalizeCharset(charsetFromDoc(doc));
             if ( filterer.charset === undefined ) {
                 streamClose(filterer);
@@ -767,6 +755,21 @@ var filterDocument = (function() {
             }
         }
 
+        if (
+            textDecoder !== undefined &&
+            textDecoder.encoding !== filterer.charset
+        ) {
+            textDecoder = undefined;
+        }
+        if ( textDecoder === undefined ) {
+            textDecoder = new TextDecoder(filterer.charset);
+        }
+
+        doc = domParser.parseFromString(
+            textDecoder.decode(filterer.buffer),
+            'text/html'
+        );
+
         var modified = false;
         if ( filterer.selectors !== undefined ) {
             if ( µb.htmlFilteringEngine.apply(doc, filterer) ) {