diff --git a/tool/fetch-bundled_gems.rb b/tool/fetch-bundled_gems.rb
index 8d04892b70..cb59b326ba 100755
--- a/tool/fetch-bundled_gems.rb
+++ b/tool/fetch-bundled_gems.rb
@@ -10,6 +10,7 @@ BEGIN {
 
 n, v, u, r = $F
 
+next unless n
 next if n =~ /^#/
 
 if File.directory?(n)