diff --git a/repos/base-hw/src/core/kernel/irq.h b/repos/base-hw/src/core/kernel/irq.h
index 2b5a7b454..c71e59c93 100644
--- a/repos/base-hw/src/core/kernel/irq.h
+++ b/repos/base-hw/src/core/kernel/irq.h
@@ -151,7 +151,9 @@ class Kernel::User_irq : public Kernel::Irq
 		 */
 		void occurred() override
 		{
-			_context.submit(1);
+			if (_context.can_submit(1)) {
+				_context.submit(1);
+			}
 			disable();
 		}
 
diff --git a/repos/base-hw/src/core/kernel/signal_receiver.cc b/repos/base-hw/src/core/kernel/signal_receiver.cc
index 691c56a3b..6c9bdac28 100644
--- a/repos/base-hw/src/core/kernel/signal_receiver.cc
+++ b/repos/base-hw/src/core/kernel/signal_receiver.cc
@@ -75,12 +75,18 @@ void Signal_context::_delivered()
 void Signal_context::_killer_cancelled() { _killer = 0; }
 
 
-int Signal_context::submit(unsigned const n)
+bool Signal_context::can_submit(unsigned const n) const
 {
-	if (_killed || _submits >= (unsigned)~0 - n) { return -1; }
+	if (_killed || _submits >= (unsigned)~0 - n) { return false; }
+	return true;
+}
+
+
+void Signal_context::submit(unsigned const n)
+{
+	if (_killed || _submits >= (unsigned)~0 - n) { return; }
 	_submits += n;
 	if (_ack) { _deliverable(); }
-	return 0;
 }
 
 
@@ -100,24 +106,33 @@ void Signal_context::ack()
 }
 
 
-int Signal_context::kill(Signal_context_killer &k)
+bool Signal_context::can_kill() const
 {
 	/* check if in a kill operation or already killed */
 	if (_killed) {
-		if (_ack) { return 0; }
-		return -1;
+		if (_ack) { return true; }
+		return false;
+	}
+	return true;
+}
+
+
+void Signal_context::kill(Signal_context_killer &k)
+{
+	/* check if in a kill operation or already killed */
+	if (_killed) {
+		return;
 	}
 	/* kill directly if there is no unacknowledged delivery */
 	if (_ack) {
 		_killed = 1;
-		return 0;
+		return;
 	}
 	/* wait for delivery acknowledgement */
 	_killer = &k;
 	_killed = 1;
 	_killer->_context = this;
 	_killer->_thread.signal_context_kill_pending();
-	return 0;
 }
 
 
@@ -194,14 +209,20 @@ void Signal_receiver::_add_context(Signal_context &c) {
 	_contexts.enqueue(c._contexts_fe); }
 
 
-int Signal_receiver::add_handler(Signal_handler &h)
+bool Signal_receiver::can_add_handler(Signal_handler const &h) const
 {
-	if (h._receiver) { return -1; }
+	if (h._receiver) { return false; }
+	return true;
+}
+
+
+void Signal_receiver::add_handler(Signal_handler &h)
+{
+	if (h._receiver) { return; }
 	_handlers.enqueue(h._handlers_fe);
 	h._receiver = this;
 	h._thread.signal_wait_for_signal();
 	_listen();
-	return 0;
 }
 
 
diff --git a/repos/base-hw/src/core/kernel/signal_receiver.h b/repos/base-hw/src/core/kernel/signal_receiver.h
index 6a3ef7927..f66c649e7 100644
--- a/repos/base-hw/src/core/kernel/signal_receiver.h
+++ b/repos/base-hw/src/core/kernel/signal_receiver.h
@@ -169,7 +169,8 @@ class Kernel::Signal_context
 		 * \retval  0 succeeded
 		 * \retval -1 failed
 		 */
-		int submit(unsigned const n);
+		bool can_submit(unsigned const n) const;
+		void submit(unsigned const n);
 
 		/**
 		 * Acknowledge delivery of signal
@@ -184,7 +185,8 @@ class Kernel::Signal_context
 		 * \retval  0 succeeded
 		 * \retval -1 failed
 		 */
-		int kill(Signal_context_killer &k);
+		bool can_kill() const;
+		void kill(Signal_context_killer &k);
 
 		/**
 		 * Create a signal context and assign it to a signal receiver
@@ -267,7 +269,8 @@ class Kernel::Signal_receiver
 		 * \retval  0 succeeded
 		 * \retval -1 failed
 		 */
-		int add_handler(Signal_handler &h);
+		bool can_add_handler(Signal_handler const &h) const;
+		void add_handler(Signal_handler &h);
 
 		/**
 		 * Syscall to create a signal receiver
diff --git a/repos/base-hw/src/core/kernel/thread.cc b/repos/base-hw/src/core/kernel/thread.cc
index 60d4ef390..fc656e5da 100644
--- a/repos/base-hw/src/core/kernel/thread.cc
+++ b/repos/base-hw/src/core/kernel/thread.cc
@@ -449,8 +449,11 @@ void Thread::timeout_triggered()
 {
 	Signal_context * const c =
 		pd().cap_tree().find<Signal_context>(_timeout_sigid);
-	if (!c || c->submit(1))
+	if (!c || !c->can_submit(1)) {
 		Genode::raw(*this, ": failed to submit timeout signal");
+		return;
+	}
+	c->submit(1);
 }
 
 
@@ -522,11 +525,12 @@ void Thread::_call_await_signal()
 		return;
 	}
 	/* register handler at the receiver */
-	if (r->add_handler(_signal_handler)) {
+	if (!r->can_add_handler(_signal_handler)) {
 		Genode::raw("failed to register handler at signal receiver");
 		user_arg_0(-1);
 		return;
 	}
+	r->add_handler(_signal_handler);
 	user_arg_0(0);
 }
 
@@ -543,10 +547,11 @@ void Thread::_call_pending_signal()
 	}
 
 	/* register handler at the receiver */
-	if (r->add_handler(_signal_handler)) {
+	if (!r->can_add_handler(_signal_handler)) {
 		user_arg_0(-1);
 		return;
 	}
+	r->add_handler(_signal_handler);
 
 	if (_state == AWAITS_SIGNAL) {
 		_cancel_blocking();
@@ -588,11 +593,12 @@ void Thread::_call_submit_signal()
 	}
 
 	/* trigger signal context */
-	if (c->submit(user_arg_2())) {
+	if (!c->can_submit(user_arg_2())) {
 		Genode::raw("failed to submit signal context");
 		user_arg_0(-1);
 		return;
 	}
+	c->submit(user_arg_2());
 	user_arg_0(0);
 }
 
@@ -622,11 +628,12 @@ void Thread::_call_kill_signal_context()
 	}
 
 	/* kill signal context */
-	if (c->kill(_signal_context_killer)) {
+	if (!c->can_kill()) {
 		Genode::raw("failed to kill signal context");
 		user_arg_0(-1);
 		return;
 	}
+	c->kill(_signal_context_killer);
 }
 
 
@@ -809,9 +816,11 @@ void Thread::_mmu_exception()
 
 	if (_core)
 		Genode::raw(*this, " raised a fault, which should never happen ",
-	                  _fault);
+		            _fault);
 
-	if (_pager) _pager->submit(1);
+	if (_pager && _pager->can_submit(1)) {
+		_pager->submit(1);
+	}
 }