diff --git a/artiq/compiler/transforms/asttyped_rewriter.py b/artiq/compiler/transforms/asttyped_rewriter.py
index 20aecdb62..084b8a7ca 100644
--- a/artiq/compiler/transforms/asttyped_rewriter.py
+++ b/artiq/compiler/transforms/asttyped_rewriter.py
@@ -263,7 +263,7 @@ class ASTTypedRewriter(algorithm.Transformer):
 
         if node.name in self.env_stack[-1]:
             diag = diagnostic.Diagnostic("fatal",
-                "variable '{name}' is already defined", {"name":name}, loc)
+                "variable '{name}' is already defined", {"name":node.name}, node.name_loc)
             self.engine.process(diag)
 
         extractor = LocalExtractor(env_stack=self.env_stack, engine=self.engine)
diff --git a/lit-test/test/inferencer/error_class.py b/lit-test/test/inferencer/error_class.py
index 0cc075b05..dbb399494 100644
--- a/lit-test/test/inferencer/error_class.py
+++ b/lit-test/test/inferencer/error_class.py
@@ -8,3 +8,9 @@ class a(1):
 class b:
     # CHECK-L: ${LINE:+1}: fatal: class body must contain only assignments and function definitions
     x += 1
+
+class c:
+    pass
+# CHECK-L: ${LINE:+1}: fatal: variable 'c' is already defined
+class c:
+    pass