diff --git a/lib/wp/object.h b/lib/wp/object.h
index b780c247..ae637f87 100644
--- a/lib/wp/object.h
+++ b/lib/wp/object.h
@@ -9,11 +9,12 @@
 #ifndef __WIREPLUMBER_OBJECT_H__
 #define __WIREPLUMBER_OBJECT_H__
 
-#include "core.h"
 #include "transition.h"
 
 G_BEGIN_DECLS
 
+typedef struct _WpCore WpCore;
+
 /*!
  * \brief Flags that specify functionality that is available on this class.
  *
diff --git a/lib/wp/plugin.c b/lib/wp/plugin.c
index f77b57bd..cb8c1c60 100644
--- a/lib/wp/plugin.c
+++ b/lib/wp/plugin.c
@@ -7,6 +7,7 @@
  */
 
 #include "plugin.h"
+#include "core.h"
 #include "log.h"
 
 WP_DEFINE_LOCAL_LOG_TOPIC ("wp-plugin")
diff --git a/lib/wp/session-item.c b/lib/wp/session-item.c
index c31af4bc..78746940 100644
--- a/lib/wp/session-item.c
+++ b/lib/wp/session-item.c
@@ -7,6 +7,7 @@
  */
 
 #include "session-item.h"
+#include "core.h"
 #include "log.h"
 #include "error.h"
 #include <spa/utils/defs.h>
diff --git a/lib/wp/session-item.h b/lib/wp/session-item.h
index 8e898b60..d4421b6e 100644
--- a/lib/wp/session-item.h
+++ b/lib/wp/session-item.h
@@ -11,6 +11,7 @@
 
 #include "object.h"
 #include "proxy.h"
+#include "properties.h"
 
 G_BEGIN_DECLS