diff --git a/include/openthread.h b/include/openthread.h
index 55bf8eaeb..1a136614c 100644
--- a/include/openthread.h
+++ b/include/openthread.h
@@ -841,7 +841,7 @@ void otSetKeySequenceCounter(uint32_t aKeySequenceCounter);
  *
  * @sa otSetNetworkIdTimeout
  */
-uint32_t otGetNetworkIdTimeout(void);
+uint8_t otGetNetworkIdTimeout(void);
 
 /**
  * Set the NETWORK_ID_TIMEOUT parameter used in the Leader role.
diff --git a/src/core/openthread.cpp b/src/core/openthread.cpp
index 90f0531ef..b25dcc4c5 100644
--- a/src/core/openthread.cpp
+++ b/src/core/openthread.cpp
@@ -391,7 +391,7 @@ void otSetKeySequenceCounter(uint32_t aKeySequenceCounter)
     sThreadNetif->GetKeyManager().SetCurrentKeySequence(aKeySequenceCounter);
 }
 
-uint32_t otGetNetworkIdTimeout(void)
+uint8_t otGetNetworkIdTimeout(void)
 {
     return sThreadNetif->GetMle().GetNetworkIdTimeout();
 }