diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 6cb99ec62000..0b1388078b69 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2900,6 +2900,17 @@ sub process {
 			}
 		}
 
+# check for invalid commit id
+		if ($in_commit_log && $line =~ /(^fixes:|\bcommit)\s+([0-9a-f]{6,40})\b/i) {
+			my $id;
+			my $description;
+			($id, $description) = git_commit_info($2, undef, undef);
+			if (!defined($id)) {
+				WARN("UNKNOWN_COMMIT_ID",
+				     "Unknown commit id '$2', maybe rebased or not pulled?\n" . $herecurr);
+			}
+		}
+
 # ignore non-hunk lines and lines being removed
 		next if (!$hunk_line || $line =~ /^-/);