diff --git a/src/main/java/de/tla2b/analysis/TypeChecker.java b/src/main/java/de/tla2b/analysis/TypeChecker.java
index 2a7463b92f013bc6f7fd5e5227efdf20a1980efd..542e34cc1fb626484739ce1d13e93148b37b037c 100644
--- a/src/main/java/de/tla2b/analysis/TypeChecker.java
+++ b/src/main/java/de/tla2b/analysis/TypeChecker.java
@@ -172,8 +172,8 @@ public class TypeChecker extends BuiltInOPs implements ASTConstants, BBuildIns,
 			OpDeclNode var = vars[i];
 			TLAType varType = (TLAType) var.getToolObject(TYPE_ID);
 			if (varType.isUntyped()) {
-				throw new TypeErrorException("Variable '" + var.getName()
-						+ "' has no type!");
+				throw new TypeErrorException("The type of the variable '" + var.getName()
+						+ "' can not be inferred: " + varType);
 			}
 		}