diff --git a/src/coreclr/gc/gc.cpp b/src/coreclr/gc/gc.cpp
index 3aa5e6ca80d10..a22eaa0398a8f 100644
--- a/src/coreclr/gc/gc.cpp
+++ b/src/coreclr/gc/gc.cpp
@@ -3493,6 +3493,7 @@ void region_allocator::make_busy_block (uint32_t* index_start, uint32_t num_unit
 #ifdef _DEBUG
     dprintf (REGIONS_LOG, ("MBB[B: %Id] %d->%d", (size_t)num_units, (int)(index_start - region_map_start), (int)(index_start - region_map_start + num_units)));
 #endif //_DEBUG
+    ASSERT_HOLDING_SPIN_LOCK (&region_allocator_lock);
     *index_start = num_units;
 }
 
@@ -3501,6 +3502,7 @@ void region_allocator::make_free_block (uint32_t* index_start, uint32_t num_unit
 #ifdef _DEBUG
     dprintf (REGIONS_LOG, ("MFB[F: %Id] %d->%d", (size_t)num_units, (int)(index_start - region_map_start), (int)(index_start - region_map_start + num_units)));
 #endif //_DEBUG
+    ASSERT_HOLDING_SPIN_LOCK (&region_allocator_lock);
     *index_start = region_alloc_free_bit | num_units;
 }
 
@@ -3519,6 +3521,7 @@ void region_allocator::adjust_map (uint32_t* current_free_index_start,
 
 void region_allocator::print_map (const char* msg)
 {
+    ASSERT_HOLDING_SPIN_LOCK (&region_allocator_lock);
 #ifdef _DEBUG
     const char* heap_type = "UH";
     dprintf (REGIONS_LOG, ("[%s]-----printing----%s", heap_type, msg));
@@ -3550,6 +3553,8 @@ uint8_t* region_allocator::allocate_end (uint32_t num_units)
 {
     uint8_t* alloc = NULL;
 
+    ASSERT_HOLDING_SPIN_LOCK (&region_allocator_lock);
+
     if (global_region_used < global_region_end)
     {
         size_t end_remaining = global_region_end - global_region_used;
@@ -3566,8 +3571,35 @@ uint8_t* region_allocator::allocate_end (uint32_t num_units)
     return alloc;
 }
 
+void region_allocator::enter_spin_lock()
+{
+    while (true)
+    {
+        if (Interlocked::CompareExchange(&region_allocator_lock.lock, 0, -1) < 0)
+            break;
+
+        while (region_allocator_lock.lock >= 0)
+        {
+            YieldProcessor();           // indicate to the processor that we are spinning
+        }
+    }
+#ifdef _DEBUG
+    region_allocator_lock.holding_thread = GCToEEInterface::GetThread();
+#endif //_DEBUG
+}
+
+void region_allocator::leave_spin_lock()
+{
+    region_allocator_lock.lock = -1;
+#ifdef _DEBUG
+    region_allocator_lock.holding_thread = (Thread*)-1;
+#endif //_DEBUG
+}
+
 uint8_t* region_allocator::allocate (uint32_t num_units)
 {
+    enter_spin_lock();
+
     uint32_t* current_index = region_map_start;
     uint32_t* end_index = region_map_end;
 
@@ -3607,6 +3639,9 @@ uint8_t* region_allocator::allocate (uint32_t num_units)
 
                 total_free_units -= num_units;
                 print_map ("alloc: found in free");
+
+                leave_spin_lock();
+
                 return region_address_of (current_free_index_start);
             }
         }
@@ -3647,6 +3682,8 @@ uint8_t* region_allocator::allocate (uint32_t num_units)
         dprintf (REGIONS_LOG, ("couldn't find memory at the end! only %Id bytes left", (global_region_end - global_region_used)));
     }
 
+    leave_spin_lock();
+
     return alloc;
 }
 
@@ -3685,6 +3722,8 @@ bool region_allocator::allocate_large_region (uint8_t** start, uint8_t** end)
 
 void region_allocator::delete_region (uint8_t* start)
 {
+    enter_spin_lock();
+
     assert (is_region_aligned (start));
 
     print_map ("before delete");
@@ -3710,6 +3749,8 @@ void region_allocator::delete_region (uint8_t* start)
 
     total_free_units += current_val;
     print_map ("after delete");
+
+    leave_spin_lock();
 }
 #endif //USE_REGIONS
 
diff --git a/src/coreclr/gc/gcpriv.h b/src/coreclr/gc/gcpriv.h
index 97c2c391db8e3..f8455ac323cd0 100644
--- a/src/coreclr/gc/gcpriv.h
+++ b/src/coreclr/gc/gcpriv.h
@@ -5329,6 +5329,11 @@ class region_allocator
     size_t region_alignment;
     size_t large_region_alignment;
 
+    GCSpinLock region_allocator_lock;
+
+    void enter_spin_lock();
+    void leave_spin_lock();
+
     uint32_t* region_map_start;
     uint32_t* region_map_end;