diff --git a/src/Value/Color.php b/src/Value/Color.php
index b8f2aff1..29dd935e 100644
--- a/src/Value/Color.php
+++ b/src/Value/Color.php
@@ -78,6 +78,7 @@ public static function parse(ParserState $oParserState, bool $bIgnoreCase = fals
             } else {
                 $sColorTarget = $sColorMode;
             }
+
             $iLength = $oParserState->strlen($sColorTarget);
             for ($i = 0; $i < $iLength; ++$i) {
                 $oParserState->consumeWhiteSpace();
@@ -85,7 +86,7 @@ public static function parse(ParserState $oParserState, bool $bIgnoreCase = fals
                     $aColor[$sColorTarget[$i]] = CSSFunction::parseIdentifierOrFunction($oParserState);
                     $bContainsVarOrCalc = true;
                 } elseif ($oParserState->comes('calc')) {
-                    $aColor[$sColorMode[$i]] = CalcFunction::parse($oParserState);
+                    $aColor[$sColorTarget[$i]] = CalcFunction::parse($oParserState);
                     $bContainsVarOrCalc = true;
                 } else {
                     $aColor[$sColorTarget[$i]] = Size::parse($oParserState, true);
@@ -101,6 +102,33 @@ public static function parse(ParserState $oParserState, bool $bIgnoreCase = fals
                     if ($oParserState->comes(',')) {
                         $oParserState->consume(',');
                     } elseif ($oParserState->comes('/')) {
+                        // According to https://developer.mozilla.org/en-US/docs/Web/CSS/color_value/rgb 
+                        // and https://developer.mozilla.org/en-US/docs/Web/CSS/color_value/hsl 
+                        // '/' is used to separate the color from the alpha channel information
+                        // in rgb or hsl color functions (it is placed before the fourth argument). 
+
+                        if (in_array($sColorMode, ["hsl", "rgb"]) && count($aColor) !== 3) {
+                            throw new UnexpectedTokenException(
+                                'Unexpected token',
+                                '/',
+                                'custom',
+                                $oParserState->currentLine()
+                            );
+                        }
+
+                        // If we have a hsl or rgb color function with an alpha channel,
+                        // we need to switch the color mode to rgba or hsla accordingly.
+                        switch ($sColorMode) {
+                            case "rgb":
+                                $sColorMode = "rgba";
+                                break;
+                            case "hsl":
+                                $sColorMode = "hsla";
+                                break;
+                            default:
+                                break;
+                        }
+
                         $oParserState->consume('/');
                     } elseif ($oParserState->comes(')')) {
                         // No alpha channel information
diff --git a/tests/ParserTest.php b/tests/ParserTest.php
index 8f1422a7..2c36caf9 100644
--- a/tests/ParserTest.php
+++ b/tests/ParserTest.php
@@ -169,7 +169,15 @@ public function colorParsing(): void
             . '#css4-rgba {background-color: rgba(242,245,249,45%);background-color: #f2f5f9;}'
             . "\n"
             . '#calc {background-color: rgba(var(--some-rgb),calc(var(--some-alpha) * .1));'
-            . 'background-color: hsla(var(--some-hsl),calc(var(--some-alpha) * .1));}',
+            . 'background-color: hsla(var(--some-hsl),calc(var(--some-alpha) * .1));}'
+            . "\n"
+            . '#hsl-calc {background-color: hsla(0,0%,10%,calc(1 - var(--hover,0) * .25));}'
+            . "\n"
+            . "#hsl-alpha-numeric {background-color: hsla(0,0%,10%,.5);}"
+            . "\n"
+            . '#rgb-calc {background-color: rgba(0,0%,10%,calc(1 - var(--hover,0) * .25));}'
+            . "\n"
+            . "#rgb-alpha-numeric {background-color: rgba(0,0%,10%,.5);}",
             $oDoc->render()
         );
     }
@@ -862,6 +870,30 @@ public function invalidRulesInFile(): void
         self::assertSame($sExpected, $oDoc->render());
     }
 
+    /**
+     * @test
+     */
+    public function invalidHslOrRgbInFile(): void 
+    {
+        $oDoc = self::parsedStructureForFile('invalid-hsl-rgb', Settings::create()->withMultibyteSupport(true));
+        $sExpected = '#hsl-1 {}'
+        . "\n"
+        . '#hsl-2 {}'
+        . "\n"
+        . '#hsl-3 {}'
+        . "\n"
+        . '#hsl-4 {}'
+        . "\n"
+        . "#rgb-1 {}"
+        . "\n"
+        . '#rgb-2 {}'
+        . "\n"
+        . '#rgb-3 {}'
+        . "\n"
+        . '#rgb-4 {}';
+        self::assertSame($sExpected, $oDoc->render());
+    }
+
     /**
      * @test
      */
diff --git a/tests/fixtures/colortest.css b/tests/fixtures/colortest.css
index 90640fb1..c22bb180 100644
--- a/tests/fixtures/colortest.css
+++ b/tests/fixtures/colortest.css
@@ -37,3 +37,20 @@
 	background-color: rgba(var(--some-rgb), calc(var(--some-alpha) * 0.1));
 	background-color: hsla(var(--some-hsl), calc(var(--some-alpha) * 0.1));
 }
+
+#hsl-calc {
+	background-color: hsl(0 0% 10% / calc(1 - var(--hover, 0) * 0.25));
+}
+
+#hsl-alpha-numeric {
+	background-color: hsl(0 0% 10% / 0.5);
+}
+
+#rgb-calc {
+	background-color: rgb(0 0% 10% / calc(1 - var(--hover, 0) * 0.25));
+}
+
+#rgb-alpha-numeric {
+	background-color: rgb(0 0% 10% / 0.5);
+}
+
diff --git a/tests/fixtures/invalid-hsl-rgb.css b/tests/fixtures/invalid-hsl-rgb.css
new file mode 100644
index 00000000..14eba7f2
--- /dev/null
+++ b/tests/fixtures/invalid-hsl-rgb.css
@@ -0,0 +1,31 @@
+#hsl-1 {
+	background-color: hsl(0 / 0% 10% 0.5);
+}
+
+#hsl-2 {
+    background-color: hsl(0 0% / 10% 0.5);
+}
+
+#hsl-3 {
+    background-color: hsl(0 0%/10% 0.5);
+}
+
+#hsl-4 {
+    background-color: hsl(0 / 0% 10% calc(1 - var(--hover, 0) * 0.25));
+}
+
+#rgb-1 {
+    background-color: rgb(0 / 0% 10% 0.5);
+}
+
+#rgb-2 {
+    background-color: rgb(0 0% / 10% 0.5);
+}
+
+#rgb-3 {
+    background-color: rgb(0 0%/10% 0.5);
+}
+
+#rgb-4 {
+    background-color: rgb(0 / 0% 10% calc(1 - var(--hover, 0) * 0.25));
+}
\ No newline at end of file