diff --git a/lib/Sabberworm/CSS/OutputFormat.php b/lib/Sabberworm/CSS/OutputFormat.php
index 1b179840..45b97f52 100644
--- a/lib/Sabberworm/CSS/OutputFormat.php
+++ b/lib/Sabberworm/CSS/OutputFormat.php
@@ -286,4 +286,4 @@ private function prepareSpace($sSpaceString) {
 	private function indent() {
 		return str_repeat($this->oFormat->sIndentation, $this->oFormat->level());
 	}
-}
\ No newline at end of file
+}
diff --git a/lib/Sabberworm/CSS/Parser.php b/lib/Sabberworm/CSS/Parser.php
index 65ea2f0d..cb22f0d1 100644
--- a/lib/Sabberworm/CSS/Parser.php
+++ b/lib/Sabberworm/CSS/Parser.php
@@ -14,7 +14,9 @@
 use Sabberworm\CSS\CSSList\AtRuleBlockList;
 use Sabberworm\CSS\RuleSet\DeclarationBlock;
 use Sabberworm\CSS\Value\CSSFunction;
+use Sabberworm\CSS\Value\CalcFunction;
 use Sabberworm\CSS\Value\RuleValueList;
+use Sabberworm\CSS\Value\CalcRuleValueList;
 use Sabberworm\CSS\Value\Size;
 use Sabberworm\CSS\Value\Color;
 use Sabberworm\CSS\Value\URL;
@@ -434,6 +436,8 @@ private function parsePrimitiveValue() {
 			$oValue = $this->parseColorValue();
 		} else if ($this->comes('url', true)) {
 			$oValue = $this->parseURLValue();
+		} else if ($this->comes('calc', true) || $this->comes('-webkit-calc', true) || $this->comes('-moz-calc', true)) {
+			$oValue = $this->parseCalcValue();
 		} else if ($this->comes("'") || $this->comes('"')) {
 			$oValue = $this->parseStringValue();
 		} else if ($this->comes("progid:") && $this->oParserSettings->bLenientParsing) {
@@ -520,6 +524,42 @@ private function parseURLValue() {
 		return $oResult;
 	}
 
+	private function parseCalcValue() {
+		$aOperators = array('+', '-', '*', '/', '(', ')');
+		$sFunction = trim($this->consumeUntil('(', false, true));
+		$oCalcList = new CalcRuleValueList($this->iLineNo);
+		$oList = new RuleValueList(',', $this->iLineNo);
+		$iNestingLevel = 0;
+		$iLastComponentType = NULL;
+		while(!$this->comes(')') || $iNestingLevel > 0) {
+			$this->consumeWhiteSpace();
+			if (in_array($this->peek(), $aOperators)) {
+				if (($this->comes('-') || $this->comes('+'))) {
+					if ($this->peek(1, -1) != ' ' || !($this->comes('- ') || $this->comes('+ '))) {
+						throw new UnexpectedTokenException(" {$this->peek()} ", $this->peek(1, -1) . $this->peek(2), 'literal', $this->iLineNo);
+					}
+				} else if ($this->comes('(')) {
+					$iNestingLevel++;
+				} else if ($this->comes(')')) {
+					$iNestingLevel--;
+				}
+				$oCalcList->addListComponent($this->consume(1));
+				$iLastComponentType = CalcFunction::T_OPERATOR;
+			} else {
+				$oVal = $this->parsePrimitiveValue();
+				if ($iLastComponentType == CalcFunction::T_OPERAND) {
+					throw new UnexpectedTokenException(sprintf('Next token was expected to be an operand of type %s. Instead "%s" was found.', implode(', ', $aOperators), $oVal), '', 'custom', $this->iLineNo);
+				}
+
+				$oCalcList->addListComponent($oVal);
+				$iLastComponentType = CalcFunction::T_OPERAND;
+			}
+		}
+		$oList->addListComponent($oCalcList);
+		$this->consume(')');
+		return new CalcFunction($sFunction, $oList, ',', $this->iLineNo);
+	}
+
 	/**
 	 * Tests an identifier for a given value. Since identifiers are all keywords, they can be vendor-prefixed. We need to check for these versions too.
 	 */
diff --git a/lib/Sabberworm/CSS/Value/CSSFunction.php b/lib/Sabberworm/CSS/Value/CSSFunction.php
index 3633abc7..941df236 100644
--- a/lib/Sabberworm/CSS/Value/CSSFunction.php
+++ b/lib/Sabberworm/CSS/Value/CSSFunction.php
@@ -4,7 +4,7 @@
 
 class CSSFunction extends ValueList {
 
-	private $sName;
+	protected $sName;
 
 	public function __construct($sName, $aArguments, $sSeparator = ',', $iLineNo = 0) {
 		if($aArguments instanceof RuleValueList) {
@@ -37,4 +37,4 @@ public function render(\Sabberworm\CSS\OutputFormat $oOutputFormat) {
 		return "{$this->sName}({$aArguments})";
 	}
 
-}
\ No newline at end of file
+}
diff --git a/lib/Sabberworm/CSS/Value/CalcFunction.php b/lib/Sabberworm/CSS/Value/CalcFunction.php
new file mode 100644
index 00000000..0dba1b85
--- /dev/null
+++ b/lib/Sabberworm/CSS/Value/CalcFunction.php
@@ -0,0 +1,8 @@
+<?php
+
+namespace Sabberworm\CSS\Value;
+
+class CalcFunction extends CSSFunction {
+	const T_OPERAND  = 1;
+	const T_OPERATOR = 2;
+}
diff --git a/lib/Sabberworm/CSS/Value/CalcRuleValueList.php b/lib/Sabberworm/CSS/Value/CalcRuleValueList.php
new file mode 100644
index 00000000..bde8a9d3
--- /dev/null
+++ b/lib/Sabberworm/CSS/Value/CalcRuleValueList.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace Sabberworm\CSS\Value;
+
+class CalcRuleValueList extends RuleValueList {
+	public function __construct($iLineNo = 0) {
+		parent::__construct(array(), ',', $iLineNo);
+	}
+
+	public function render(\Sabberworm\CSS\OutputFormat $oOutputFormat) {
+		return $oOutputFormat->implode(' ', $this->aComponents);
+	}
+
+}
diff --git a/tests/Sabberworm/CSS/ParserTest.php b/tests/Sabberworm/CSS/ParserTest.php
index 6df3e872..ec3b9f84 100644
--- a/tests/Sabberworm/CSS/ParserTest.php
+++ b/tests/Sabberworm/CSS/ParserTest.php
@@ -387,6 +387,20 @@ function testUrlInFile() {
 		$this->assertSame($sExpected, $oDoc->render());
 	}
 
+	function testCalcInFile() {
+		$oDoc = $this->parsedStructureForFile('calc', Settings::create()->withMultibyteSupport(true));
+		$sExpected = 'div {width: calc(100% / 4);}
+div {height: -webkit-calc(9 / 16 * 100%) !important;width: -moz-calc(( 50px - 50% ) * 2);}';
+		$this->assertSame($sExpected, $oDoc->render());
+	}
+
+	/**
+	* @expectedException Sabberworm\CSS\Parsing\UnexpectedTokenException
+	*/
+	function testCalcFailure() {
+		$this->parsedStructureForFile('-calc-no-space-around-minus', Settings::create()->withLenientParsing(false));
+	}
+
 	function testUrlInFileMbOff() {
 		$oDoc = $this->parsedStructureForFile('url', Settings::create()->withMultibyteSupport(false));
 		$sExpected = 'body {background: #fff url("http://somesite.com/images/someimage.gif") repeat top center;}
diff --git a/tests/files/-calc-no-space-around-minus.css b/tests/files/-calc-no-space-around-minus.css
new file mode 100644
index 00000000..9414ad16
--- /dev/null
+++ b/tests/files/-calc-no-space-around-minus.css
@@ -0,0 +1 @@
+div { width: calc(50% -8px); }
diff --git a/tests/files/calc.css b/tests/files/calc.css
new file mode 100644
index 00000000..3ad06fdd
--- /dev/null
+++ b/tests/files/calc.css
@@ -0,0 +1,5 @@
+div { width: calc(100% / 4); }
+div {
+	height: -webkit-calc(9/16 * 100%)!important;
+	width: -moz-calc((50px - 50%)*2);
+}