diff --git a/action.yml b/action.yml
index d8537d5..d6544e6 100644
--- a/action.yml
+++ b/action.yml
@@ -1,6 +1,6 @@
-name: PR Comment from File
-author: Alexander Matheson <awmatheson@github.com>
-description: Leaves a comment on an open PR based on the contents of a file.
+name: PR Comment and Update from File
+author: Alexander Matheson <awmatheson@github.com> Ethan Graf <ethan.graf@fuzzbuzz.io>
+description: Leaves a comment on an open PR based on the contents of a file. If a comment with the right prefix exists, update instead.
 branding:
   icon: 'message-square'  
   color: 'black'
@@ -8,8 +8,12 @@ inputs:
   path: 
     description: file path
     required: true
+  prefix:
+    description: comment prefix
+    required: true
 runs:
   using: 'docker'
   image: 'Dockerfile'
   args:
-    - ${{ inputs.path }}
\ No newline at end of file
+    - ${{ inputs.path }}
+    - ${{ inputs.prefix }}
\ No newline at end of file
diff --git a/entrypoint.sh b/entrypoint.sh
index eadd404..497a900 100755
--- a/entrypoint.sh
+++ b/entrypoint.sh
@@ -13,8 +13,8 @@ if !ENV["GITHUB_TOKEN"]
   exit(1)
 end
 
-if ARGV.empty?
-  puts "Missing file path argument."
+if ARGV.length < 2
+  puts "Missing arguments."
   exit(1)
 end
 
@@ -35,6 +35,7 @@ else
   pr_number = pr["number"]
 end
 file_path = ARGV[0]
+prefix = ARGV[1]
 
 puts Dir.entries(".")
 
@@ -42,4 +43,9 @@ message = File.read(file_path)
 
 coms = github.issue_comments(repo, pr_number)
 
-github.add_comment(repo, pr_number, message)
+com = coms.find { |com| com["body"].start_with?(prefix) }
+if com == nil
+  github.add_comment(repo, pr_number, prefix + "\n\n" + message)
+else
+  com = github.update_comment(repo, com["id"], com["body"] + "\n\n" + message)
+end