diff --git a/lib/rubygems/core_ext/kernel_require.rb b/lib/rubygems/core_ext/kernel_require.rb
index 89e3e33db2..4759f26090 100755
--- a/lib/rubygems/core_ext/kernel_require.rb
+++ b/lib/rubygems/core_ext/kernel_require.rb
@@ -38,7 +38,7 @@ module Kernel
 
     resolved_path = begin
       rp = nil
-      $LOAD_PATH[0...Gem.load_path_insert_index].each do |lp|
+      $LOAD_PATH[0...Gem.load_path_insert_index || -1].each do |lp|
         Gem.suffixes.each do |s|
           full_path = File.join(lp, "#{path}#{s}")
           if File.file?(File.expand_path(full_path))