diff --git a/compose/const.py b/compose/const.py
index 75774867a..89c6f2eb3 100644
--- a/compose/const.py
+++ b/compose/const.py
@@ -58,7 +58,7 @@ API_VERSIONS = {
     COMPOSEFILE_V3_5: '1.30',
     COMPOSEFILE_V3_6: '1.36',
     COMPOSEFILE_V3_7: '1.38',
-    COMPOSEFILE_V3_8: '1.38',
+    COMPOSEFILE_V3_8: '1.40',
 }
 
 API_VERSION_TO_ENGINE_VERSION = {