diff --git a/src/coreclr/gc/gc.cpp b/src/coreclr/gc/gc.cpp
index 217e90d38c0228..e0f084cd0338df 100644
--- a/src/coreclr/gc/gc.cpp
+++ b/src/coreclr/gc/gc.cpp
@@ -6404,7 +6404,11 @@ class heap_select
         if (GCToOSInterface::CanGetCurrentProcessorNumber())
         {
             uint32_t proc_no = GCToOSInterface::GetCurrentProcessorNumber();
-            proc_no_to_heap_no[proc_no] = (uint16_t)heap_number;
+            // For a 32-bit process running on a machine with > 64 procs, 
+            // even though the process can only use up to 32 procs, the processor 
+            // index can be >= 64; or in the cpu group case, if the process is not running in cpu group #0, 
+            // the GetCurrentProcessorNumber will return a number that's >= 64.
+            proc_no_to_heap_no[proc_no % MAX_SUPPORTED_CPUS] = (uint16_t)heap_number;
         }
     }
 
@@ -6426,7 +6430,11 @@ class heap_select
         if (GCToOSInterface::CanGetCurrentProcessorNumber())
         {
             uint32_t proc_no = GCToOSInterface::GetCurrentProcessorNumber();
-            int adjusted_heap = proc_no_to_heap_no[proc_no];
+            // For a 32-bit process running on a machine with > 64 procs, 
+            // even though the process can only use up to 32 procs, the processor 
+            // index can be >= 64; or in the cpu group case, if the process is not running in cpu group #0, 
+            // the GetCurrentProcessorNumber will return a number that's >= 64.
+            int adjusted_heap = proc_no_to_heap_no[proc_no % MAX_SUPPORTED_CPUS];
             // with dynamic heap count, need to make sure the value is in range.
             if (adjusted_heap >= gc_heap::n_heaps)
             {