diff --git a/common.mk b/common.mk
index 84d1dce13f..5d115985d9 100644
--- a/common.mk
+++ b/common.mk
@@ -13472,6 +13472,7 @@ ractor.$(OBJEXT): $(top_srcdir)/internal/gc.h
 ractor.$(OBJEXT): $(top_srcdir)/internal/hash.h
 ractor.$(OBJEXT): $(top_srcdir)/internal/imemo.h
 ractor.$(OBJEXT): $(top_srcdir)/internal/numeric.h
+ractor.$(OBJEXT): $(top_srcdir)/internal/ractor.h
 ractor.$(OBJEXT): $(top_srcdir)/internal/rational.h
 ractor.$(OBJEXT): $(top_srcdir)/internal/sanitizers.h
 ractor.$(OBJEXT): $(top_srcdir)/internal/serial.h
diff --git a/internal/ractor.h b/internal/ractor.h
index eef5ffdb89..a65907a05a 100644
--- a/internal/ractor.h
+++ b/internal/ractor.h
@@ -3,4 +3,8 @@
 
 void rb_ractor_ensure_main_ractor(const char *msg);
 
+RUBY_SYMBOL_EXPORT_BEGIN
+void rb_ractor_setup_belonging(VALUE obj);
+RUBY_SYMBOL_EXPORT_END
+
 #endif /* INTERNAL_RACTOR_H */
diff --git a/ractor.c b/ractor.c
index 0913c526ea..68c64c4035 100644
--- a/ractor.c
+++ b/ractor.c
@@ -12,6 +12,7 @@
 #include "internal/error.h"
 #include "internal/gc.h"
 #include "internal/hash.h"
+#include "internal/ractor.h"
 #include "internal/rational.h"
 #include "internal/struct.h"
 #include "internal/thread.h"