diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/cdtvariables/EnvironmentVariableSupplier.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/cdtvariables/EnvironmentVariableSupplier.java
index 33af789267f..a74254d8f5a 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/cdtvariables/EnvironmentVariableSupplier.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/cdtvariables/EnvironmentVariableSupplier.java
@@ -101,7 +101,7 @@ public class EnvironmentVariableSupplier extends CoreMacroSupplierBase {
 	}
 	
 	private static boolean isTextList(String str, String delimiter) {
-		if (delimiter == null || delimiter.isEmpty())
+		if (str == null || delimiter == null || delimiter.isEmpty())
 			return false;
 		
 		// Regex: ([^:]+:)+[^:]*