diff --git a/waflib/Options.py b/waflib/Options.py
index db679531..0276de05 100644
--- a/waflib/Options.py
+++ b/waflib/Options.py
@@ -141,9 +141,9 @@ class OptionsContext(Context.Context):
 		gr.add_option('-o', '--out', action='store', default='', help='build dir for the project', dest='out')
 		gr.add_option('-t', '--top', action='store', default='', help='src dir for the project', dest='top')
 
-		gr.add_option('--no-lock-in-run', action='store_true', default='', help=optparse.SUPPRESS_HELP, dest='no_lock_in_run')
-		gr.add_option('--no-lock-in-out', action='store_true', default='', help=optparse.SUPPRESS_HELP, dest='no_lock_in_out')
-		gr.add_option('--no-lock-in-top', action='store_true', default='', help=optparse.SUPPRESS_HELP, dest='no_lock_in_top')
+		gr.add_option('--no-lock-in-run', action='store_true', default=os.environ.get('NO_LOCK_IN_RUN', ''), help=optparse.SUPPRESS_HELP, dest='no_lock_in_run')
+		gr.add_option('--no-lock-in-out', action='store_true', default=os.environ.get('NO_LOCK_IN_OUT', ''), help=optparse.SUPPRESS_HELP, dest='no_lock_in_out')
+		gr.add_option('--no-lock-in-top', action='store_true', default=os.environ.get('NO_LOCK_IN_TOP', ''), help=optparse.SUPPRESS_HELP, dest='no_lock_in_top')
 
 		default_prefix = getattr(Context.g_module, 'default_prefix', os.environ.get('PREFIX'))
 		if not default_prefix:
diff --git a/waflib/Scripting.py b/waflib/Scripting.py
index 68dccf29..da83a216 100644
--- a/waflib/Scripting.py
+++ b/waflib/Scripting.py
@@ -306,7 +306,7 @@ def distclean(ctx):
 
 	# remove a build folder, if any
 	cur = '.'
-	if ctx.options.no_lock_in_top:
+	if os.environ.get('NO_LOCK_IN_TOP') or ctx.options.no_lock_in_top:
 		cur = ctx.options.out
 
 	try:
@@ -333,9 +333,9 @@ def distclean(ctx):
 			remove_and_log(env.out_dir, shutil.rmtree)
 
 		env_dirs = [env.out_dir]
-		if not ctx.options.no_lock_in_top:
+		if not (os.environ.get('NO_LOCK_IN_TOP') or ctx.options.no_lock_in_top):
 			env_dirs.append(env.top_dir)
-		if not ctx.options.no_lock_in_run:
+		if not (os.environ.get('NO_LOCK_IN_RUN') or ctx.options.no_lock_in_run):
 			env_dirs.append(env.run_dir)
 		for k in env_dirs:
 			p = os.path.join(k, Options.lockfile)