diff --git a/bypy/linux/site.py b/bypy/linux/site.py
index e3870eb394..4e0dbf556b 100644
--- a/bypy/linux/site.py
+++ b/bypy/linux/site.py
@@ -33,9 +33,6 @@ def set_helper():
 
 def main():
     sys.argv[0] = sys.calibre_basename
-    dfv = os.environ.get('CALIBRE_DEVELOP_FROM')
-    if dfv and os.path.exists(dfv):
-        sys.path.insert(0, os.path.abspath(dfv))
     set_helper()
     setup_openssl_environment()
     set_quit()
diff --git a/bypy/macos/site.py b/bypy/macos/site.py
index da270e4517..b017184ad3 100644
--- a/bypy/macos/site.py
+++ b/bypy/macos/site.py
@@ -46,9 +46,6 @@ def main():
         except Exception:
             pass
 
-    dfv = os.environ.get('CALIBRE_DEVELOP_FROM')
-    if dfv and os.path.exists(dfv):
-        sys.path.insert(0, os.path.abspath(dfv))
     set_helper()
     set_quit()
     if sys.gui_app and not (
diff --git a/bypy/windows/site.py b/bypy/windows/site.py
index 952c23bbbb..30775fe293 100644
--- a/bypy/windows/site.py
+++ b/bypy/windows/site.py
@@ -42,12 +42,6 @@ class PydImporter:
         pyd_items = None
 
 
-def add_calibre_vars():
-    dv = os.environ.get('CALIBRE_DEVELOP_FROM', None)
-    if dv and os.path.exists(dv):
-        sys.path.insert(0, os.path.abspath(dv))
-
-
 def run_entry_point():
     bname, mod, func = sys.calibre_basename, sys.calibre_module, sys.calibre_function
     sys.argv[0] = bname + '.exe'
@@ -77,7 +71,6 @@ def main():
     linecache.orig_getline = linecache.getline
     linecache.getline = fake_getline
 
-    add_calibre_vars()
     set_helper()
     set_quit()