diff --git a/README.md b/README.md
index b32cc2d..9203e9a 100644
--- a/README.md
+++ b/README.md
@@ -97,6 +97,7 @@ Usage:
 
   battery discharge LEVEL[1-100]
     block power input from the adapter until battery falls to this level
+    should not be used when your laptop is used in clamshell mode
     eg: battery discharge 90
 
   battery visudo
diff --git a/battery.sh b/battery.sh
index c8c51b6..99d5fce 100755
--- a/battery.sh
+++ b/battery.sh
@@ -88,6 +88,7 @@ Usage:
 
   battery discharge LEVEL[1-100]
     block power input from the adapter until battery falls to this level
+    should not be used when your laptop is used in clamshell mode
     eg: battery discharge 90
 
   battery visudo