diff --git a/src/commands/diff.rs b/src/commands/diff.rs
index df0eb1f..250be60 100644
--- a/src/commands/diff.rs
+++ b/src/commands/diff.rs
@@ -18,7 +18,7 @@ use crate::{
         PullRequestUpdate,
     },
     message::{MessageSection, validate_commit_message},
-    output::{output, write_commit_title},
+    output::{output, write_commit_info, write_commit_title},
     utils::{parse_name_list, remove_all_parens, slugify},
 };
 use git2::Oid;
@@ -435,6 +435,49 @@ async fn diff_impl(
         }
     }
 
+    if let Some(ref pull_request) = pull_request
+        && config.check_for_commits_from_others
+    {
+        let last_pr_commit = git.repo().find_commit(pull_request.head_oid)?;
+        let last_pr_committer = last_pr_commit.committer();
+        let local_commit = git.repo().find_commit(local_commit.oid)?;
+        let local_committer = local_commit.committer();
+        if local_committer.name() != last_pr_committer.name() {
+            let commit_id = last_pr_commit.id().to_string();
+            let summary = last_pr_commit.summary().unwrap_or("<title unknown>");
+            let pr_committer = last_pr_committer.name().unwrap_or("unknown");
+            output("⚠️", "The last PR commit is not from you:")?;
+            write_commit_info(&commit_id[0..7], &summary, &pr_committer)?;
+            let pr_branch_name = pull_request.head.branch_name().to_string();
+            let input = tokio::task::spawn_blocking(move || {
+                dialoguer::Input::<String>::new()
+                    .with_prompt(formatdoc!(
+                        "
+
+                            Please select what you want do:
+                            1) Type 'yes' to continue (risks losing changes from others)
+                            2) Hit Enter to stop
+
+                            Then manually merge in the changes from the PR:
+
+                            git fetch origin {pr_branch_name}
+                            git merge --squash origin/{pr_branch_name}
+                            git commit --amend
+
+                            Then run `spr diff` again.
+
+                            ",
+                    ))
+                    .allow_empty(true)
+                    .interact_text()
+            })
+            .await??;
+            if input.is_empty() || input != "yes" {
+                bail!("Aborted as per user request");
+            }
+        }
+    }
+
     // Check if there is a base branch on GitHub already. That's the case when
     // there is an existing Pull Request, and its base is not the master branch.
     let base_branch = if let Some(ref pr) = pull_request {
diff --git a/src/config.rs b/src/config.rs
index f054c61..cee1033 100644
--- a/src/config.rs
+++ b/src/config.rs
@@ -18,6 +18,7 @@ pub struct Config {
     pub auth_token: String,
     pub require_approval: bool,
     pub require_test_plan: bool,
+    pub check_for_commits_from_others: bool,
 }
 
 impl Config {
@@ -30,6 +31,7 @@ impl Config {
         auth_token: String,
         require_approval: bool,
         require_test_plan: bool,
+        check_for_commits_from_others: bool,
     ) -> Self {
         let master_ref =
             GitHubBranch::new_from_branch_name(&master_branch, &master_branch);
@@ -41,6 +43,7 @@ impl Config {
             auth_token,
             require_approval,
             require_test_plan,
+            check_for_commits_from_others,
         }
     }
 
@@ -106,6 +109,7 @@ mod tests {
             "xyz".into(),
             false,
             true,
+            false,
         )
     }
 
diff --git a/src/main.rs b/src/main.rs
index 2d77961..6e7f1a3 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -138,6 +138,10 @@ pub async fn spr() -> Result<()> {
         .get_bool("spr.requireTestPlan")
         .ok()
         .unwrap_or(true);
+    let check_for_commits_from_others = git_config
+        .get_bool("spr.checkForCommitsFromOthers")
+        .ok()
+        .unwrap_or(false);
 
     let github_auth_token = match cli.github_auth_token {
         Some(v) => Ok(v),
@@ -152,6 +156,7 @@ pub async fn spr() -> Result<()> {
         github_auth_token.clone(),
         require_approval,
         require_test_plan,
+        check_for_commits_from_others,
     );
     debug!("config: {:?}", config);
 
diff --git a/src/output.rs b/src/output.rs
index e8e54c8..28dffa2 100644
--- a/src/output.rs
+++ b/src/output.rs
@@ -42,3 +42,18 @@ pub fn write_commit_title(prepared_commit: &PreparedCommit) -> Result<()> {
     ))?;
     Ok(())
 }
+
+pub fn write_commit_info(
+    short_id: &str,
+    title: &str,
+    committer: &str,
+) -> Result<()> {
+    let term = console::Term::stdout();
+    term.write_line(&format!(
+        "{} {} (from {})",
+        console::style(short_id).italic(),
+        console::style(title).yellow(),
+        console::style(committer)
+    ))?;
+    Ok(())
+}