diff --git a/README.md b/README.md
index e4e29a30..18c1aaf5 100644
--- a/README.md
+++ b/README.md
@@ -695,13 +695,13 @@ Closes the app and leaves it running in the background.
 
     - Type: launch_app
       Role: role1
-      Value: com.android.vending (Optional - Android app package / iOS bundle ID)
+      Value: com.android.vending (Android app package / iOS bundle ID)
 
 ### <a id="terminate_app"></a>terminate_app
 
     - Type: terminate_app
       Role: role1
-      Value: com.apple.Preferences (Optional - Android app package / iOS bundle ID)
+      Value: com.apple.Preferences (Android app package / iOS bundle ID)
 
 ### <a id="start_record/end_record"></a>start_record/end_record (Mobile)
 
diff --git a/lib/core/device.rb b/lib/core/device.rb
index c7da1457..fba1c171 100644
--- a/lib/core/device.rb
+++ b/lib/core/device.rb
@@ -250,34 +250,28 @@ def close_app(action = nil)
   # launches the app specified by the Android app package / iOS bundle ID
   # defaults to the app under test if Value is not provided
   # Accepts:
-  #   Value (optional)
+  #   Value
   def launch_app(action)
+    raise "Please specify the application identifier in the Value field!" unless action.key?("Value")
     app_id = action["Value"]
-    if app_id
-      if @platform == "iOS"
-        @driver.execute_script('mobile: launchApp', {'bundleId': app_id})
-      elsif @platform == "Android"
-        @driver.activate_app(app_id)
-      end
-    else
-      @driver.launch_app
+    if @platform == "iOS"
+      @driver.execute_script('mobile: launchApp', {'bundleId': app_id})
+    elsif @platform == "Android"
+      @driver.execute_script('mobile: activateApp', {'appId': app_id})
     end
   end
 
   # closes the app specified by the Android app package / iOS bundle ID
   # defaults to the app under test if Value is not provided
   # Accepts:
-  #   Value (optional)
+  #   Value
   def terminate_app(action)
+    raise "Please specify the application identifier in the Value field!" unless action.key?("Value")
     app_id = action["Value"]
-    if app_id
-      if @platform == "iOS"
-        @driver.execute_script('mobile: terminateApp', {'bundleId': app_id})
-      elsif @platform == "Android"
-        @driver.terminate_app(app_id)
-      end
-    else
-      @driver.close_app
+    if @platform == "iOS"
+      @driver.execute_script('mobile: terminateApp', {'bundleId': app_id})
+    elsif @platform == "Android"
+      @driver.execute_script('mobile: terminateApp', {'appId': app_id})
     end
   end