diff --git a/data/schemas/keyboard.jsonschema b/data/schemas/keyboard.jsonschema
index c55d66e6bbf..2c6a7f527c7 100644
--- a/data/schemas/keyboard.jsonschema
+++ b/data/schemas/keyboard.jsonschema
@@ -34,7 +34,7 @@
         },
         "development_board": {
             "type": "string",
-            "enum": ["promicro", "elite_c", "proton_c", "kb2040", "promicro_rp2040", "blok", "bit_c_pro", "bluepill", "blackpill_f401", "blackpill_f411"]
+            "enum": ["promicro", "elite_c", "proton_c", "kb2040", "promicro_rp2040", "blok", "bit_c_pro", "stemcell", "bluepill", "blackpill_f401", "blackpill_f411"]
         },
         "pin_compatible": {
             "type": "string",
diff --git a/quantum/keymap_extras/keymap_us_extended.h b/quantum/keymap_extras/keymap_us_extended.h
index fb3e9c7d36a..8e71a8de25a 100644
--- a/quantum/keymap_extras/keymap_us_extended.h
+++ b/quantum/keymap_extras/keymap_us_extended.h
@@ -145,7 +145,7 @@
 #define US_CURR ALGR(US_4)    // ¤
 #define US_EURO ALGR(US_5)    // €
 #define US_DCIR ALGR(US_6)    // ^ (dead)
-#define US_HORN ALGR(US_7)    // ̛̛  (dead)
+#define US_HORN ALGR(US_7)    // ̛  (dead)
 #define US_OGON ALGR(US_8)    // ˛ (dead)
 #define US_LSQU ALGR(US_9)    // ‘
 #define US_RSQU ALGR(US_0)    // ’