1 files changed, 1 insertions, 1 deletions
diff --git a/newgrf_text.c b/newgrf_text.c
index 85f3cd32f..04566bac6 100644
--- a/newgrf_text.c
+++ b/newgrf_text.c
@@ -164,7 +164,7 @@ static void TranslateTTDPatchCodes(char *str)
 			case 0x98: *c = 31; break;
 			default:
 				/* Validate any unhandled character */
-				if (!IsValidAsciiChar(*c)) *c = '?';
+				if (!IsValidAsciiChar(*c, CS_ALPHANUMERAL)) *c = '?';
 				break;
 		}
 	}