diff --git a/quimb/tensor/tensor_core.py b/quimb/tensor/tensor_core.py
index 96f36c7d..e8cdb2e4 100644
--- a/quimb/tensor/tensor_core.py
+++ b/quimb/tensor/tensor_core.py
@@ -10436,7 +10436,7 @@ def full_simplify(
 
         if check_zero == "auto":
             # any method but R checks data entries anyway
-            check_zero == bool(set(seq) - {"R"})
+            check_zero = bool(set(seq) - {"R"})
 
         tn.squeeze_(exclude=output_inds)