diff --git a/proto/AbilityMixinCostStamina.proto b/proto/AbilityMixinCostStamina.proto
new file mode 100644
index 000000000..a9000d479
--- /dev/null
+++ b/proto/AbilityMixinCostStamina.proto
@@ -0,0 +1,7 @@
+syntax = "proto3";
+
+option java_package = "emu.grasscutter.net.proto";
+
+message AbilityMixinCostStamina {
+  bool is_swim = 1;
+}