diff --git a/l2tdevtools/source_helper.py b/l2tdevtools/source_helper.py
index 1f008469..4946494f 100644
--- a/l2tdevtools/source_helper.py
+++ b/l2tdevtools/source_helper.py
@@ -265,11 +265,12 @@ def Clean(self):
       return
 
     filenames_to_ignore = re.compile(
-        '^{0:s}-.*{1!s}'.format(self.project_name, project_version))
+        '^{0:s}-(|experimental-|alpha-|beta-){1!s}'.format(
+            self.project_name, project_version))
 
     # Remove previous versions of source packages in the format:
     # project-*.tar.gz
-    filenames = glob.glob('{0:s}-*.tar.gz'.format(self.project_name))
+    filenames = glob.glob('{0:s}-[0-9]*.tar.gz'.format(self.project_name))
     for filename in filenames:
       if not filenames_to_ignore.match(filename):
         logging.info('Removing: {0:s}'.format(filename))
@@ -277,7 +278,7 @@ def Clean(self):
 
     # Remove previous versions of source packages in the format:
     # project-*.tgz
-    filenames = glob.glob('{0:s}-*.tgz'.format(self.project_name))
+    filenames = glob.glob('{0:s}-[0-9]*.tgz'.format(self.project_name))
     for filename in filenames:
       if not filenames_to_ignore.match(filename):
         logging.info('Removing: {0:s}'.format(filename))
@@ -285,7 +286,7 @@ def Clean(self):
 
     # Remove previous versions of source packages in the format:
     # project-*.zip
-    filenames = glob.glob('{0:s}-*.zip'.format(self.project_name))
+    filenames = glob.glob('{0:s}-[0-9]*.zip'.format(self.project_name))
     for filename in filenames:
       if not filenames_to_ignore.match(filename):
         logging.info('Removing: {0:s}'.format(filename))
@@ -293,7 +294,7 @@ def Clean(self):
 
     # Remove previous versions of source directories in the format:
     # project-{version}
-    filenames = glob.glob('{0:s}-*'.format(self.project_name))
+    filenames = glob.glob('{0:s}-[0-9]*'.format(self.project_name))
     for filename in filenames:
       if os.path.isdir(filename) and not filenames_to_ignore.match(filename):
         logging.info('Removing: {0:s}'.format(filename))