diff --git a/base-hw/src/base/thread/thread_bootstrap.cc b/base-hw/src/base/thread/thread_bootstrap.cc
index 2642874f4..999cdb937 100644
--- a/base-hw/src/base/thread/thread_bootstrap.cc
+++ b/base-hw/src/base/thread/thread_bootstrap.cc
@@ -91,4 +91,5 @@ void Thread_base::_init_platform_thread(Type type)
 	}
 	/* adjust initial object state in case of a main thread */
 	tid().thread_id = _main_thread_id;
+	_thread_cap     = env()->parent()->main_thread_cap();
 }
diff --git a/base-okl4/src/base/thread/thread_bootstrap.cc b/base-okl4/src/base/thread/thread_bootstrap.cc
index e0cdb88d1..b9996f936 100644
--- a/base-okl4/src/base/thread/thread_bootstrap.cc
+++ b/base-okl4/src/base/thread/thread_bootstrap.cc
@@ -14,6 +14,7 @@
 
 /* Genode includes */
 #include <base/thread.h>
+#include <base/env.h>
 
 /* OKL4 includes */
 namespace Okl4
@@ -82,4 +83,5 @@ void Genode::Thread_base::_init_platform_thread(Type type)
 {
 	if (type == NORMAL) { return; }
 	_tid.l4id.raw = main_thread_tid.raw;
+	_thread_cap   = env()->parent()->main_thread_cap();
 }
diff --git a/base-pistachio/src/base/thread/thread_bootstrap.cc b/base-pistachio/src/base/thread/thread_bootstrap.cc
index f6941728f..f7da3caae 100644
--- a/base-pistachio/src/base/thread/thread_bootstrap.cc
+++ b/base-pistachio/src/base/thread/thread_bootstrap.cc
@@ -13,6 +13,7 @@
 
 /* Genode includes */
 #include <base/thread.h>
+#include <base/env.h>
 
 /* Pistachio includes */
 namespace Pistachio
@@ -48,5 +49,6 @@ void Genode::Thread_base::_thread_bootstrap()
 void Genode::Thread_base::_init_platform_thread(Type type)
 {
 	if (type == NORMAL) { return; }
-	_tid.l4id = main_thread_tid;
+	_tid.l4id   = main_thread_tid;
+	_thread_cap = env()->parent()->main_thread_cap();
 }