--- old/src/hotspot/share/gc/shenandoah/shenandoahPacer.cpp	2019-11-21 11:54:14.020002898 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahPacer.cpp	2019-11-21 11:54:13.763998568 +0100
@@ -191,7 +191,7 @@
 void ShenandoahPacer::restart_with(size_t non_taxable_bytes, double tax_rate) {
   size_t initial = (size_t)(non_taxable_bytes * tax_rate) >> LogHeapWordSize;
   STATIC_ASSERT(sizeof(size_t) <= sizeof(intptr_t));
-  Atomic::xchg((intptr_t)initial, &_budget);
+  Atomic::xchg(&_budget, (intptr_t)initial);
   Atomic::store(&_tax_rate, tax_rate);
   Atomic::inc(&_epoch);
 }