diff --git a/include/kernel.h b/include/kernel.h
index 7edb398d40f..c5764b14730 100644
--- a/include/kernel.h
+++ b/include/kernel.h
@@ -4841,7 +4841,7 @@ extern int k_mem_slab_init(struct k_mem_slab *slab, void *buffer,
  * This routine allocates a memory block from a memory slab.
  *
  * @note @a timeout must be set to K_NO_WAIT if called from ISR.
- * @note When CONFIG_MULTITHREADING=n any @timeout is treated as K_NO_WAIT.
+ * @note When CONFIG_MULTITHREADING=n any @a timeout is treated as K_NO_WAIT.
  *
  * @funcprops \isr_ok
  *
@@ -4962,6 +4962,7 @@ void k_heap_init(struct k_heap *h, void *mem, size_t bytes);
  * k_heap_free().
  *
  * @note @a timeout must be set to K_NO_WAIT if called from ISR.
+ * @note When CONFIG_MULTITHREADING=n any @a timeout is treated as K_NO_WAIT.
  *
  * @funcprops \isr_ok
  *
@@ -4985,6 +4986,7 @@ void *k_heap_aligned_alloc(struct k_heap *h, size_t align, size_t bytes,
  * the timeout, NULL will be returned.
  *
  * @note @a timeout must be set to K_NO_WAIT if called from ISR.
+ * @note When CONFIG_MULTITHREADING=n any @a timeout is treated as K_NO_WAIT.
  *
  * @funcprops \isr_ok
  *
diff --git a/kernel/kheap.c b/kernel/kheap.c
index a3217dd30af..7683d050702 100644
--- a/kernel/kheap.c
+++ b/kernel/kheap.c
@@ -39,7 +39,8 @@ void *k_heap_aligned_alloc(struct k_heap *h, size_t align, size_t bytes,
 		ret = sys_heap_aligned_alloc(&h->heap, align, bytes);
 
 		now = sys_clock_tick_get();
-		if ((ret != NULL) || ((end - now) <= 0)) {
+		if (!IS_ENABLED(CONFIG_MULTITHREADING) ||
+		    (ret != NULL) || ((end - now) <= 0)) {
 			break;
 		}
 
@@ -58,7 +59,7 @@ void k_heap_free(struct k_heap *h, void *mem)
 
 	sys_heap_free(&h->heap, mem);
 
-	if (z_unpend_all(&h->wait_q) != 0) {
+	if (IS_ENABLED(CONFIG_MULTITHREADING) && z_unpend_all(&h->wait_q) != 0) {
 		z_reschedule(&h->lock, key);
 	} else {
 		k_spin_unlock(&h->lock, key);