diff --git a/lya_2pt/output.py b/lya_2pt/output.py
index 46edf07..9503584 100644
--- a/lya_2pt/output.py
+++ b/lya_2pt/output.py
@@ -229,7 +229,7 @@ def write_optimal_cf(
         correlation_samples = np.array([result for result in output.values()])
 
         output_fits.write(
-            [correlation_samples],
+            correlation_samples,
             names=[correlation_name],
             comment=['unnormalized correlation'],
             header=header,