diff --git a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
index f7d65771034..46616cb32be 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp
@@ -151,6 +151,7 @@ jint ShenandoahHeap::initialize() {
   Universe::check_alignment(init_byte_size, reg_size_bytes, "Shenandoah heap");
 
   _num_regions = ShenandoahHeapRegion::region_count();
+  assert(_num_regions == (max_byte_size / reg_size_bytes), "Must match");
 
   // Now we know the number of regions, initialize the heuristics.
   initialize_heuristics();
diff --git a/src/hotspot/share/gc/shenandoah/shenandoahHeapRegion.cpp b/src/hotspot/share/gc/shenandoah/shenandoahHeapRegion.cpp
index 2dd5f161d1d..ceba74d0544 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahHeapRegion.cpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahHeapRegion.cpp
@@ -573,7 +573,7 @@ void ShenandoahHeapRegion::setup_sizes(size_t max_heap_size) {
   RegionSizeBytesMask = RegionSizeBytes - 1;
 
   guarantee(RegionCount == 0, "we should only set it once");
-  RegionCount = max_heap_size / RegionSizeBytes;
+  RegionCount = align_up(max_heap_size, RegionSizeBytes) / RegionSizeBytes;
   guarantee(RegionCount >= MIN_NUM_REGIONS, "Should have at least minimum regions");
 
   guarantee(HumongousThresholdWords == 0, "we should only set it once");