diff --git a/esphome/core/config.py b/esphome/core/config.py
index 2d87796987..80b731b905 100644
--- a/esphome/core/config.py
+++ b/esphome/core/config.py
@@ -394,7 +394,7 @@ async def to_code(config):
     if project_conf := config.get(CONF_PROJECT):
         cg.add_define("ESPHOME_PROJECT_NAME", project_conf[CONF_NAME])
         cg.add_define("ESPHOME_PROJECT_VERSION", project_conf[CONF_VERSION])
-        cg.add_define("ESPHOME_PROJECT_VERSION_30", project_conf[CONF_VERSION][:30])
+        cg.add_define("ESPHOME_PROJECT_VERSION_30", project_conf[CONF_VERSION][:29])
         for conf in project_conf.get(CONF_ON_UPDATE, []):
             trigger = cg.new_Pvariable(conf[CONF_TRIGGER_ID])
             await cg.register_component(trigger, conf)