diff --git a/src/general.c b/src/general.c
index 6036b695..5fbb668c 100644
--- a/src/general.c
+++ b/src/general.c
@@ -19,7 +19,8 @@
     }
 
 /*
- * Reads size bytes into the destination buffer from filename.
+ * Reads (size - 1) bytes into the destination buffer from filename,
+ * and null-terminate it.
  *
  * On success, true is returned. Otherwise, false is returned and the content
  * of destination is left untouched.
diff --git a/src/print_battery_info.c b/src/print_battery_info.c
index 8864978b..8f454562 100644
--- a/src/print_battery_info.c
+++ b/src/print_battery_info.c
@@ -161,6 +161,11 @@ static bool slurp_battery_info(battery_info_ctx_t *ctx, struct battery_info *bat
     }
 
     for (walk = buf, last = buf; (walk - buf) < 1024; walk++) {
+        // `*walk` (slice of `buf`) is only initialised until `null` written by `slurp()`
+        if (*walk == '\0') {
+            break;
+        }
+
         if (*walk == '\n') {
             last = walk + 1;
             continue;