diff --git a/.github/comment-body-addition.md b/.github/comment-body-addition.md
index 30f398d9..706143fa 100644
--- a/.github/comment-body-addition.md
+++ b/.github/comment-body-addition.md
@@ -1 +1 @@
-**Edit:** Some additional info
+This is still the second line.
\ No newline at end of file
diff --git a/.github/comment-body.md b/.github/comment-body.md
index 465112f4..6f774b79 100644
--- a/.github/comment-body.md
+++ b/.github/comment-body.md
@@ -1,5 +1,2 @@
 This is a multi-line test comment read from a file.
-- With GitHub **Markdown** :sparkles:
-- Created by [create-or-update-comment][1]
-
-[1]: https://github.com/peter-evans/create-or-update-comment
+This is the second line.
\ No newline at end of file
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 75b1e830..42bca922 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -112,6 +112,7 @@ jobs:
         with:
           comment-id: ${{ steps.couc2.outputs.comment-id }}
           body-file: .github/comment-body-addition.md
+          append-separator: 'space'
           reactions: eyes, rocket
 
   package:
diff --git a/action.yml b/action.yml
index e708102a..bbf0e1ab 100644
--- a/action.yml
+++ b/action.yml
@@ -18,6 +18,9 @@ inputs:
   edit-mode:
     description: 'The mode when updating a comment, "replace" or "append".'
     default: 'append'
+  append-separator:
+    description: 'The separator to use when appending to an existing comment. (`newline`, `space`, `none`)'
+    default: 'newline'
   reactions:
     description: 'A comma or newline separated list of reactions to add to the comment.'
 outputs:
diff --git a/dist/index.js b/dist/index.js
index 55cbaf9b..b15c6725 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -98,6 +98,16 @@ function addReactions(octokit, owner, repo, commentId, reactions) {
         }
     });
 }
+function appendSeparator(body, separator) {
+    switch (separator) {
+        case 'newline':
+            return body + '\n';
+        case 'space':
+            return body + ' ';
+        default: // none
+            return body;
+    }
+}
 function createOrUpdateComment(inputs) {
     return __awaiter(this, void 0, void 0, function* () {
         const [owner, repo] = inputs.repository.split('/');
@@ -118,7 +128,7 @@ function createOrUpdateComment(inputs) {
                         repo: repo,
                         comment_id: inputs.commentId
                     });
-                    commentBody = comment.body + '\n';
+                    commentBody = appendSeparator(comment.body ? comment.body : '', inputs.appendSeparator);
                 }
                 commentBody = commentBody + body;
                 core.debug(`Comment body: ${commentBody}`);
@@ -220,6 +230,7 @@ function run() {
                 body: core.getInput('body'),
                 bodyFile: core.getInput('body-file'),
                 editMode: core.getInput('edit-mode'),
+                appendSeparator: core.getInput('append-separator'),
                 reactions: utils.getInputAsArray('reactions')
             };
             core.debug(`Inputs: ${(0, util_1.inspect)(inputs)}`);
@@ -227,6 +238,10 @@ function run() {
                 core.setFailed(`Invalid edit-mode '${inputs.editMode}'.`);
                 return;
             }
+            if (!['newline', 'space', 'none'].includes(inputs.appendSeparator)) {
+                core.setFailed(`Invalid append-separator '${inputs.appendSeparator}'.`);
+                return;
+            }
             if (inputs.bodyFile && inputs.body) {
                 core.setFailed("Only one of 'body' or 'body-file' can be set.");
                 return;
diff --git a/src/create-or-update-comment.ts b/src/create-or-update-comment.ts
index dd11e48f..c9af3237 100644
--- a/src/create-or-update-comment.ts
+++ b/src/create-or-update-comment.ts
@@ -10,6 +10,7 @@ export interface Inputs {
   body: string
   bodyFile: string
   editMode: string
+  appendSeparator: string
   reactions: string[]
 }
 
@@ -83,6 +84,17 @@ async function addReactions(
   }
 }
 
+function appendSeparator(body: string, separator: string): string {
+  switch (separator) {
+    case 'newline':
+      return body + '\n'
+    case 'space':
+      return body + ' '
+    default: // none
+      return body
+  }
+}
+
 export async function createOrUpdateComment(inputs: Inputs): Promise<void> {
   const [owner, repo] = inputs.repository.split('/')
   const body = getBody(inputs)
@@ -105,7 +117,10 @@ export async function createOrUpdateComment(inputs: Inputs): Promise<void> {
           repo: repo,
           comment_id: inputs.commentId
         })
-        commentBody = comment.body + '\n'
+        commentBody = appendSeparator(
+          comment.body ? comment.body : '',
+          inputs.appendSeparator
+        )
       }
 
       commentBody = commentBody + body
diff --git a/src/main.ts b/src/main.ts
index 2de7d545..e8bfa0ac 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -14,6 +14,7 @@ async function run(): Promise<void> {
       body: core.getInput('body'),
       bodyFile: core.getInput('body-file'),
       editMode: core.getInput('edit-mode'),
+      appendSeparator: core.getInput('append-separator'),
       reactions: utils.getInputAsArray('reactions')
     }
     core.debug(`Inputs: ${inspect(inputs)}`)
@@ -23,6 +24,11 @@ async function run(): Promise<void> {
       return
     }
 
+    if (!['newline', 'space', 'none'].includes(inputs.appendSeparator)) {
+      core.setFailed(`Invalid append-separator '${inputs.appendSeparator}'.`)
+      return
+    }
+
     if (inputs.bodyFile && inputs.body) {
       core.setFailed("Only one of 'body' or 'body-file' can be set.")
       return