diff --git a/src/main/java/com/inet/sass/parser/LexicalUnitImpl.java b/src/main/java/com/inet/sass/parser/LexicalUnitImpl.java
index 29b7408..f549e74 100644
--- a/src/main/java/com/inet/sass/parser/LexicalUnitImpl.java
+++ b/src/main/java/com/inet/sass/parser/LexicalUnitImpl.java
@@ -680,6 +680,7 @@ public SassListItem evaluateFunctionsAndExpressions( ScssContext context, boolea
                     // log unknown functions
                     switch( functionName.toLowerCase() ) {
                         case "brightness":
+                        case "contrast":
                         case "counters":
                         case "hsl":
                         case "hsla":