diff --git a/src/lib/reducer.js b/src/lib/reducer.js
index a82ca93..e7f3340 100644
--- a/src/lib/reducer.js
+++ b/src/lib/reducer.js
@@ -28,7 +28,7 @@ function isValueType(type) {
     case 'VminValue':
     case 'VmaxValue':
     case 'PercentageValue':
-    case 'Value':
+    case 'Number':
       return true;
   }
   return false;
@@ -236,7 +236,7 @@ function reduceDivisionExpression(node) {
     return node;
   }
 
-  if (node.right.type !== 'Value') {
+  if (node.right.type !== 'Number') {
     throw new Error(`Cannot divide by "${node.right.unit}", number expected`);
   }
 
@@ -253,8 +253,8 @@ function reduceDivisionExpression(node) {
 }
 
 function reduceMultiplicationExpression(node) {
-  // (expr) * value
-  if (node.left.type === 'MathExpression' && node.right.type === 'Value') {
+  // (expr) * number
+  if (node.left.type === 'MathExpression' && node.right.type === 'Number') {
     if (
       isValueType(node.left.left.type) &&
       isValueType(node.left.right.type)
@@ -264,13 +264,13 @@ function reduceMultiplicationExpression(node) {
       return node.left;
     }
   }
-  // something * value
-  else if (isValueType(node.left.type) && node.right.type === 'Value') {
+  // something * number
+  else if (isValueType(node.left.type) && node.right.type === 'Number') {
     node.left.value *= node.right.value;
     return node.left;
   }
-  // value * (expr)
-  else if (node.left.type === 'Value' && node.right.type === 'MathExpression') {
+  // number * (expr)
+  else if (node.left.type === 'Number' && node.right.type === 'MathExpression') {
     if (
       isValueType(node.right.left.type) &&
       isValueType(node.right.right.type)
@@ -280,8 +280,8 @@ function reduceMultiplicationExpression(node) {
       return node.right;
     }
   }
-  // value * something
-  else if (node.left.type === 'Value' && isValueType(node.right.type)) {
+  // number * something
+  else if (node.left.type === 'Number' && isValueType(node.right.type)) {
     node.right.value *= node.left.value;
     return node.right;
   }
diff --git a/src/lib/stringifier.js b/src/lib/stringifier.js
index e2ccbbc..d8e1bff 100644
--- a/src/lib/stringifier.js
+++ b/src/lib/stringifier.js
@@ -35,7 +35,7 @@ function stringify(node, prec) {
 
       return str;
     }
-    case "Value":
+    case 'Number':
       return round(node.value, prec);
     case 'Function':
       return node.value;
diff --git a/src/parser.jison b/src/parser.jison
index 892cbc1..eb402b8 100644
--- a/src/parser.jison
+++ b/src/parser.jison
@@ -76,15 +76,15 @@ expression
     | math_expression DIV math_expression { $$ = { type: 'MathExpression', operator: $2, left: $1, right: $3 }; }
     | LPAREN math_expression RPAREN { $$ = $2; }
     | function { $$ = $1; }
-    | css_value { $$ = $1; }
-    | value { $$ = $1; }
+    | dimension { $$ = $1; }
+    | number { $$ = $1; }
     ;
 
   function
     : FUNCTION { $$ = { type: 'Function', value: $1 }; }
     ;
 
-  css_value
+  dimension
     : LENGTH { $$ = { type: 'LengthValue', value: parseFloat($1), unit: /[a-z]+$/i.exec($1)[0] }; }
     | ANGLE { $$ = { type: 'AngleValue', value: parseFloat($1), unit: /[a-z]+$/i.exec($1)[0] }; }
     | TIME { $$ = { type: 'TimeValue', value: parseFloat($1), unit: /[a-z]+$/i.exec($1)[0] }; }
@@ -100,12 +100,12 @@ expression
     | VMINS { $$ = { type: 'VminValue', value: parseFloat($1), unit: 'vmin' }; }
     | VMAXS { $$ = { type: 'VmaxValue', value: parseFloat($1), unit: 'vmax' }; }
     | PERCENTAGE { $$ = { type: 'PercentageValue', value: parseFloat($1), unit: '%' }; }
-    | ADD css_value { var prev = $2; $$ = prev; }
-    | SUB css_value { var prev = $2; prev.value *= -1; $$ = prev; }
+    | ADD dimension { var prev = $2; $$ = prev; }
+    | SUB dimension { var prev = $2; prev.value *= -1; $$ = prev; }
     ;
 
-  value
-    : NUMBER { $$ = { type: 'Value', value: parseFloat($1) }; }
-    | ADD NUMBER { $$ = { type: 'Value', value: parseFloat($2) }; }
-    | SUB NUMBER { $$ = { type: 'Value', value: parseFloat($2) * -1 }; }
+  number
+    : NUMBER { $$ = { type: 'Number', value: parseFloat($1) }; }
+    | ADD NUMBER { $$ = { type: 'Number', value: parseFloat($2) }; }
+    | SUB NUMBER { $$ = { type: 'Number', value: parseFloat($2) * -1 }; }
     ;