diff --git a/src/cli.cr b/src/cli.cr
index af8c431..2e8eedd 100644
--- a/src/cli.cr
+++ b/src/cli.cr
@@ -127,7 +127,7 @@ module CodePreloader
 
       STDERR.puts "Processing source directories: #{source_list}".colorize(:yellow)
       processed_files = [] of ProcessedFile
-      filelist.each do |file_path|
+      filelist.to_a.sort.each do |file_path|
         STDERR.puts "Processing file: #{file_path}".colorize(:yellow)
         file_result = process_file(file_path, output_file)
         processed_files << file_result
diff --git a/src/filelist.cr b/src/filelist.cr
index d66d3af..2ccb99d 100644
--- a/src/filelist.cr
+++ b/src/filelist.cr
@@ -46,7 +46,7 @@ module CodePreloader
       seen = Set(String).new
 
       # walk each source
-      @sources.each do |dir|
+      @sources.sort.each do |dir|
         walker = Walk::Down.new(dir)
 
         walker = walker.filter do |path|
@@ -88,7 +88,7 @@ module CodePreloader
       self.each do |path|
         files << path.to_s
       end
-      files
+      files.sort
     end
   end
 end