diff --git a/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml b/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml
index 1df8ffe95fc6..62f97da1b2fd 100644
--- a/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml
+++ b/Documentation/devicetree/bindings/serial/st,stm32-uart.yaml
@@ -58,6 +58,9 @@ properties:
 
   wakeup-source: true
 
+  power-domains:
+    maxItems: 1
+
   rx-threshold:
     description:
       If value is set to 1, RX FIFO threshold is disabled.