diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4bfcf0fa..46fc107a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -40,6 +40,7 @@ Please also have a look at our
 
 ### Removed
 
+- Remove the IE hack in `Rule` (#995)
 - Drop `getLineNo()` from the `Renderable` interface (#1038)
 - Remove `OutputFormat::level()` (#874)
 - Remove expansion of shorthand properties (#838)
diff --git a/config/phpstan-baseline.neon b/config/phpstan-baseline.neon
index f2969599..e17e1b3f 100644
--- a/config/phpstan-baseline.neon
+++ b/config/phpstan-baseline.neon
@@ -234,12 +234,6 @@ parameters:
 			count: 1
 			path: ../src/Rule/Rule.php
 
-		-
-			message: '#^Construct empty\(\) is not allowed\. Use more strict comparison\.$#'
-			identifier: empty.notAllowed
-			count: 1
-			path: ../src/Rule/Rule.php
-
 		-
 			message: '#^Only booleans are allowed in an if condition, Sabberworm\\CSS\\Value\\RuleValueList\|string\|null given\.$#'
 			identifier: if.condNotBoolean
@@ -258,12 +252,6 @@ parameters:
 			count: 1
 			path: ../src/Rule/Rule.php
 
-		-
-			message: '#^Parameters should have "string" types as the only types passed to this method$#'
-			identifier: typePerfect.narrowPublicClassMethodParamType
-			count: 1
-			path: ../src/Rule/Rule.php
-
 		-
 			message: '#^Call to an undefined method Sabberworm\\CSS\\OutputFormat\:\:comments\(\)\.$#'
 			identifier: method.notFound
diff --git a/src/Parsing/ParserState.php b/src/Parsing/ParserState.php
index b4885c17..2100ed35 100644
--- a/src/Parsing/ParserState.php
+++ b/src/Parsing/ParserState.php
@@ -150,13 +150,6 @@ public function parseIdentifier($ignoreCase = true)
     public function parseCharacter($isForIdentifier)
     {
         if ($this->peek() === '\\') {
-            if (
-                $isForIdentifier && $this->parserSettings->usesLenientParsing()
-                && ($this->comes('\\0') || $this->comes('\\9'))
-            ) {
-                // Non-strings can contain \0 or \9 which is an IE hack supported in lenient parsing.
-                return null;
-            }
             $this->consume('\\');
             if ($this->comes('\\n') || $this->comes('\\r')) {
                 return '';
diff --git a/src/Rule/Rule.php b/src/Rule/Rule.php
index 45cf24d0..0ec26902 100644
--- a/src/Rule/Rule.php
+++ b/src/Rule/Rule.php
@@ -36,11 +36,6 @@ class Rule implements Renderable, Commentable
      */
     private $isImportant = false;
 
-    /**
-     * @var array<int, int>
-     */
-    private $ieHack = [];
-
     /**
      * @var int
      */
@@ -91,13 +86,6 @@ public static function parse(ParserState $parserState): Rule
         $parserState->consume(':');
         $value = Value::parseValue($parserState, self::listDelimiterForRule($rule->getRule()));
         $rule->setValue($value);
-        if ($parserState->getSettings()->usesLenientParsing()) {
-            while ($parserState->comes('\\')) {
-                $parserState->consume('\\');
-                $rule->addIeHack($parserState->consume());
-                $parserState->consumeWhiteSpace();
-            }
-        }
         $parserState->consumeWhiteSpace();
         if ($parserState->comes('!')) {
             $parserState->consume('!');
@@ -220,30 +208,6 @@ public function addValue($value, $type = ' '): void
         }
     }
 
-    /**
-     * @param int $modifier
-     */
-    public function addIeHack($modifier): void
-    {
-        $this->ieHack[] = $modifier;
-    }
-
-    /**
-     * @param array<int, int> $modifiers
-     */
-    public function setIeHack(array $modifiers): void
-    {
-        $this->ieHack = $modifiers;
-    }
-
-    /**
-     * @return array<int, int>
-     */
-    public function getIeHack()
-    {
-        return $this->ieHack;
-    }
-
     /**
      * @param bool $isImportant
      */
@@ -276,9 +240,6 @@ public function render(OutputFormat $outputFormat): string
         } else {
             $result .= $this->value;
         }
-        if (!empty($this->ieHack)) {
-            $result .= ' \\' . \implode('\\', $this->ieHack);
-        }
         if ($this->isImportant) {
             $result .= ' !important';
         }
diff --git a/src/Value/Value.php b/src/Value/Value.php
index dcd8686a..c14d74fa 100644
--- a/src/Value/Value.php
+++ b/src/Value/Value.php
@@ -50,7 +50,6 @@ public static function parseValue(ParserState $parserState, array $aListDelimite
         while (
         !($parserState->comes('}') || $parserState->comes(';') || $parserState->comes('!')
             || $parserState->comes(')')
-            || $parserState->comes('\\')
             || $parserState->isEnd())
         ) {
             if (\count($aStack) > 0) {
diff --git a/tests/ParserTest.php b/tests/ParserTest.php
index 7a66f852..040011b7 100644
--- a/tests/ParserTest.php
+++ b/tests/ParserTest.php
@@ -1036,28 +1036,6 @@ public function unexpectedTokenExceptionLineNo(): void
         }
     }
 
-    /**
-     * @test
-     */
-    public function ieHacksStrictParsing(): void
-    {
-        $this->expectException(UnexpectedTokenException::class);
-
-        // We can't strictly parse IE hacks.
-        self::parsedStructureForFile('ie-hacks', Settings::create()->beStrict());
-    }
-
-    /**
-     * @test
-     */
-    public function ieHacksParsing(): void
-    {
-        $document = self::parsedStructureForFile('ie-hacks', Settings::create()->withLenientParsing(true));
-        $expected = 'p {padding-right: .75rem \\9;background-image: none \\9;color: red \\9\\0;'
-            . 'background-color: red \\9\\0;background-color: red \\9\\0 !important;content: "red 	\\0";content: "red઼";}';
-        self::assertSame($expected, $document->render());
-    }
-
     /**
      * @depends files
      *
diff --git a/tests/fixtures/ie-hacks.css b/tests/fixtures/ie-hacks.css
deleted file mode 100644
index 3f5f215e..00000000
--- a/tests/fixtures/ie-hacks.css
+++ /dev/null
@@ -1,9 +0,0 @@
-p {
-    padding-right: .75rem \9;
-    background-image: none \9;
-    color:red\9\0;
-    background-color:red \9 \0;
-    background-color:red \9 \0 !important;
-    content: "red \9\0";
-    content: "red\0abc";
-}