diff --git a/com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/IgnoreOS.java b/com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/IgnoreOS.java
index 0be605720b6299850a916cb0fb4261605df83e9d..b478fbf2a9bcd5be775eb6fcccf882037d09ad6e 100644
--- a/com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/IgnoreOS.java
+++ b/com.oracle.truffle.r.test/src/com/oracle/truffle/r/test/IgnoreOS.java
@@ -44,7 +44,7 @@ public enum IgnoreOS implements TestTrait {
 
     private boolean isIgnoring() {
         String current = System.getProperty("os.name");
-        return current != null && current.contains(osName);
+        return current != null && current.toLowerCase().contains(osName);
     }
 
     @Override