diff --git a/hw/ppc/spapr_rng.c b/hw/ppc/spapr_rng.c
index a39d472b66..02d6be49f5 100644
--- a/hw/ppc/spapr_rng.c
+++ b/hw/ppc/spapr_rng.c
@@ -77,13 +77,13 @@ static target_ulong h_random(PowerPCCPU *cpu, sPAPRMachineState *spapr,
     hrdata.val.v64 = 0;
     hrdata.received = 0;
 
-    qemu_mutex_unlock_iothread();
     while (hrdata.received < 8) {
         rng_backend_request_entropy(rngstate->backend, 8 - hrdata.received,
                                     random_recv, &hrdata);
+        qemu_mutex_unlock_iothread();
         qemu_sem_wait(&hrdata.sem);
+        qemu_mutex_lock_iothread();
     }
-    qemu_mutex_lock_iothread();
 
     qemu_sem_destroy(&hrdata.sem);
     args[0] = hrdata.val.v64;