diff --git a/scripts/options.py b/scripts/options.py
index 4d2bbee..5de2f58 100644
--- a/scripts/options.py
+++ b/scripts/options.py
@@ -23,7 +23,7 @@ import json, os, deps
 
 def check_options(dir = '.'):
     global options, options_mtime
-    options = { "show_threads": str(os.getenv("SHOW_THREADS")) }
+    options = { "show_threads": str(os.getenv("NOPSCADLIB_SHOW_THREADS")) }
     options_fname = dir + '/options.json'
     try:
         with open(options_fname) as json_file:
diff --git a/utils/thread.scad b/utils/thread.scad
index b464ae1..3937415 100644
--- a/utils/thread.scad
+++ b/utils/thread.scad
@@ -31,7 +31,7 @@
 //!
 //! Making the ends requires a CGAL intersection, which make threads relatively slow. For this reason they are generally disabled when using the GUI but can
 //! be enabled by setting ```$show_threads``` to ```true```. When the tests are run, by default, threads are enabled only for things that feature them like screws.
-//! This behaviour can be changed by setting a ```SHOW_THREADS``` environment variable to ```false``` to disable all threads and ```true``` to enable all threads.
+//! This behaviour can be changed by setting a ```NOPSCADLIB_SHOW_THREADS``` environment variable to ```false``` to disable all threads and ```true``` to enable all threads.
 //! The same variable also affects the generation of assembly diagrams.
 //!
 //! Threads obey the $fn, $fa, $fs variables.