diff --git a/hw/timer/armv7m_systick.c b/hw/timer/armv7m_systick.c
index 3bd951dd04..5dfe39afe3 100644
--- a/hw/timer/armv7m_systick.c
+++ b/hw/timer/armv7m_systick.c
@@ -149,6 +149,10 @@ static MemTxResult systick_write(void *opaque, hwaddr addr,
         s->control &= 0xfffffff8;
         s->control |= value & 7;
 
+        if ((oldval ^ value) & SYSTICK_CLKSOURCE) {
+            systick_set_period_from_clock(s);
+        }
+
         if ((oldval ^ value) & SYSTICK_ENABLE) {
             if (value & SYSTICK_ENABLE) {
                 ptimer_run(s->ptimer, 0);
@@ -156,10 +160,6 @@ static MemTxResult systick_write(void *opaque, hwaddr addr,
                 ptimer_stop(s->ptimer);
             }
         }
-
-        if ((oldval ^ value) & SYSTICK_CLKSOURCE) {
-            systick_set_period_from_clock(s);
-        }
         ptimer_transaction_commit(s->ptimer);
         break;
     }