diff --git a/src/core/meshcop/meshcop.hpp b/src/core/meshcop/meshcop.hpp
index a118f4b2b..7f0655840 100644
--- a/src/core/meshcop/meshcop.hpp
+++ b/src/core/meshcop/meshcop.hpp
@@ -55,9 +55,6 @@
 #include "meshcop/steering_data.hpp"
 
 namespace ot {
-
-class ThreadNetif;
-
 namespace MeshCoP {
 
 /**
diff --git a/src/core/thread/child_supervision.hpp b/src/core/thread/child_supervision.hpp
index 3e833a3ad..2eb0b77f4 100644
--- a/src/core/thread/child_supervision.hpp
+++ b/src/core/thread/child_supervision.hpp
@@ -51,8 +51,6 @@
 
 namespace ot {
 
-class ThreadNetif;
-
 /**
  *
  * Child supervision feature provides a mechanism for parent
diff --git a/src/core/utils/jam_detector.hpp b/src/core/utils/jam_detector.hpp
index a4be7a532..b20f67fce 100644
--- a/src/core/utils/jam_detector.hpp
+++ b/src/core/utils/jam_detector.hpp
@@ -47,9 +47,6 @@
 #include "common/timer.hpp"
 
 namespace ot {
-
-class ThreadNetif;
-
 namespace Utils {
 
 class JamDetector : public InstanceLocator, private NonCopyable