diff --git a/lib/os/heap.c b/lib/os/heap.c
index b23d160b726..b361a784308 100644
--- a/lib/os/heap.c
+++ b/lib/os/heap.c
@@ -128,6 +128,23 @@ static void merge_chunks(struct z_heap *h, chunkid_t lc, chunkid_t rc)
 
 	set_chunk_size(h, lc, newsz);
 	set_left_chunk_size(h, right_chunk(h, rc), newsz);
+
+#if defined(__arc__) && defined(__GNUC__)
+	/* This is a workaround for a compiler bug on (at least) GCC
+	 * 12.1.0 in Zephyr SDK 0.15.1.  The optimizer generates this
+	 * function with a last instruction that is an unconditional
+	 * branch (a tail call into the chunk_set() handling).  But
+	 * that means that the NEXT instruction gets decoded as part
+	 * of the branch delay slot, but that instruction isn't part
+	 * of this function!  Some instructions aren't legal in branch
+	 * delay slots.  One of those is ENTER_S, which is a very
+	 * common entry instruction for whatever function the linker
+	 * places after us.  It seems like the compiler doesn't
+	 * understand this problem.  Stuff a NOP in to guarantee the
+	 * code is legal.
+	 */
+	__asm__ volatile("nop");
+#endif
 }
 
 static void free_chunk(struct z_heap *h, chunkid_t c)