diff --git a/hw/misc/npcm_clk.c b/hw/misc/npcm_clk.c
index d1f29759d5..0e85974cf9 100644
--- a/hw/misc/npcm_clk.c
+++ b/hw/misc/npcm_clk.c
@@ -964,8 +964,9 @@ static void npcm_clk_enter_reset(Object *obj, ResetType type)
     NPCMCLKState *s = NPCM_CLK(obj);
     NPCMCLKClass *c = NPCM_CLK_GET_CLASS(s);
 
-    g_assert(sizeof(s->regs) >= c->nr_regs * sizeof(uint32_t));
-    memcpy(s->regs, c->cold_reset_values, sizeof(s->regs));
+    size_t sizeof_regs = c->nr_regs * sizeof(uint32_t);
+    g_assert(sizeof(s->regs) >= sizeof_regs);
+    memcpy(s->regs, c->cold_reset_values, sizeof_regs);
     s->ref_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
     npcm7xx_clk_update_all_clocks(s);
     /*