diff --git a/repos/base-hw/src/core/kernel/cpu.h b/repos/base-hw/src/core/kernel/cpu.h
index e47d1adf73..35ab1b0014 100644
--- a/repos/base-hw/src/core/kernel/cpu.h
+++ b/repos/base-hw/src/core/kernel/cpu.h
@@ -171,7 +171,7 @@ class Kernel::Cpu : public Genode::Cpu, private Irq::Pool, private Timeout
 		/**
 		 * Returns the currently active job
 		 */
-		Job & scheduled_job() const {
+		Job & scheduled_job() {
 			return *static_cast<Job *>(&_scheduler.head())->helping_destination(); }
 
 		unsigned id() const { return _id; }
diff --git a/repos/base-hw/src/core/kernel/cpu_scheduler.cc b/repos/base-hw/src/core/kernel/cpu_scheduler.cc
index fd600e73d2..c97d49285d 100644
--- a/repos/base-hw/src/core/kernel/cpu_scheduler.cc
+++ b/repos/base-hw/src/core/kernel/cpu_scheduler.cc
@@ -313,9 +313,12 @@ void Cpu_scheduler::quota(Share &s, unsigned const q)
 }
 
 
-Cpu_share &Cpu_scheduler::head() const
+Cpu_share &Cpu_scheduler::head()
 {
-	assert(_head);
+	if (!_head) {
+		Genode::error("attempt to access invalid scheduler head");
+		update(_last_time);
+	}
 	return *_head;
 }
 
diff --git a/repos/base-hw/src/core/kernel/cpu_scheduler.h b/repos/base-hw/src/core/kernel/cpu_scheduler.h
index a1e4a0770f..4699292f40 100644
--- a/repos/base-hw/src/core/kernel/cpu_scheduler.h
+++ b/repos/base-hw/src/core/kernel/cpu_scheduler.h
@@ -233,7 +233,7 @@ class Kernel::Cpu_scheduler
 		 * Accessors
 		 */
 
-		Share &head() const;
+		Share &head();
 		unsigned head_quota() const {
 			return Genode::min(_head_quota, _residual); }
 		unsigned quota() const { return _quota; }