diff --git a/src/gamelog.cpp b/src/gamelog.cpp
--- a/src/gamelog.cpp
+++ b/src/gamelog.cpp
@@ -51,8 +51,8 @@ static const char * GetGamelogRevisionSt
 		return _openttd_revision;
 	} else if (gamelog_revision[0] == 0) {
 		/* Prefix character indication revision status */
-		assert(_openttd_revision_modified < 3);
-		gamelog_revision[0] = "gum"[_openttd_revision_modified]; // g = "git", u = "unknown", m = "modified"
+		assert(_openttd_revision_modified < 5);
+		gamelog_revision[0] = "gumhh"[_openttd_revision_modified]; // g = "git", u = "unknown", m = "modified", "h" = "hg"
 		/* Append the revision hash */
 		strecat(gamelog_revision, _openttd_revision_hash, lastof(gamelog_revision));
 		/* Truncate string to GAMELOG_REVISION_LENGTH bytes */