diff --git a/base-foc/src/platform/_main_helper.h b/base-foc/src/platform/_main_helper.h
index 062412083..0c63dad70 100644
--- a/base-foc/src/platform/_main_helper.h
+++ b/base-foc/src/platform/_main_helper.h
@@ -21,15 +21,24 @@
 
 namespace Fiasco {
 #include <l4/sys/utcb.h>
-#include <l4/sys/kdebug.h>
 }
 
 enum { MAIN_THREAD_CAP_ID = 1 };
 
 static void main_thread_bootstrap() {
-	Fiasco::l4_utcb_tcr()->user[Fiasco::UTCB_TCR_BADGE]      = MAIN_THREAD_CAP_ID;
-	Fiasco::l4_utcb_tcr()->user[Fiasco::UTCB_TCR_THREAD_OBJ] = 0;
-	Genode::cap_map()->insert(MAIN_THREAD_CAP_ID, Fiasco::MAIN_THREAD_CAP);
+	/**
+	 * Unfortunately ldso calls this function twice. So the second time when
+	 * inserting the main thread's gate-capability an exception would be raised.
+	 * At least on ARM we got problems when raising an exception that early,
+	 * that's why we first check if the cap is already registered before
+	 * inserting it.
+	 */
+	Genode::Cap_index *idx = Genode::cap_map()->find(MAIN_THREAD_CAP_ID);
+	if (!idx) {
+		Fiasco::l4_utcb_tcr()->user[Fiasco::UTCB_TCR_BADGE]      = MAIN_THREAD_CAP_ID;
+		Fiasco::l4_utcb_tcr()->user[Fiasco::UTCB_TCR_THREAD_OBJ] = 0;
+		Genode::cap_map()->insert(MAIN_THREAD_CAP_ID, Fiasco::MAIN_THREAD_CAP);
+	}
 }