diff --git a/libtbx/auto_build/conda_build/create_custom_bin.py b/libtbx/auto_build/conda_build/create_custom_bin.py
index 38a660f64a..03ea15257b 100644
--- a/libtbx/auto_build/conda_build/create_custom_bin.py
+++ b/libtbx/auto_build/conda_build/create_custom_bin.py
@@ -83,7 +83,7 @@ def copy_bin(prefix, custom_bin, packages=[]):
 
   namespace = parser.parse_args()
 
-  copy_bin(namespace.prefix, namespace.custom_bin, namespace.packages)
+  copy_bin(namespace.prefix, namespace.custom_bin.lower(), namespace.packages)
 
 # =============================================================================
 # end