diff --git a/tmux.c b/tmux.c
index 31070f00..196edf6c 100644
--- a/tmux.c
+++ b/tmux.c
@@ -132,7 +132,7 @@ parseenvironment(void)
 	if ((env = getenv("TMUX")) == NULL)
 		return;
 
-	if (sscanf(env, "%255s,%ld,%d", path, &pid, &idx) != 3)
+	if (sscanf(env, "%255[^,],%ld,%d", path, &pid, &idx) != 3)
 		return;
 	environ_path = xstrdup(path);
 	environ_pid = pid;
diff --git a/tty-keys.c b/tty-keys.c
index 3381aefe..223d574e 100644
--- a/tty-keys.c
+++ b/tty-keys.c
@@ -630,10 +630,10 @@ tty_keys_mouse(struct tty *tty,
 				utf8_append(&utf8data, buf[*size]);
 				value = utf8_combine(&utf8data);
 			} else
-				value = buf[*size];
+				value = (unsigned char)buf[*size];
 			(*size)++;
 		} else {
-			value = buf[*size];
+			value = (unsigned char)buf[*size];
 			(*size)++;
 		}