diff --git a/src/mzscheme/gc2/compact.c b/src/mzscheme/gc2/compact.c
index dafb6f1509..aa034d904a 100644
--- a/src/mzscheme/gc2/compact.c
+++ b/src/mzscheme/gc2/compact.c
@@ -10,6 +10,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include "platforms.h"
 #include "gc2.h"
 
 #define NUMBER_OF_TAGS 512
@@ -160,7 +161,7 @@ unsigned long (*GC_get_thread_stack_base)(void);
 void (*GC_mark_xtagged)(void *obj);
 void (*GC_fixup_xtagged)(void *obj);
 
-void **GC_variable_stack;
+THREAD_LOCAL void **GC_variable_stack;
 
 void **GC_get_variable_stack() { return GC_variable_stack; }
 void GC_set_variable_stack(void **p) { GC_variable_stack = p; }
diff --git a/src/mzscheme/gc2/gc2.h b/src/mzscheme/gc2/gc2.h
index dbf7251cb3..3c27e79b35 100644
--- a/src/mzscheme/gc2/gc2.h
+++ b/src/mzscheme/gc2/gc2.h
@@ -262,7 +262,7 @@ GC2_EXTERN void GC_finalization_weak_ptr(void **p, int offset);
 /* Cooperative GC                                                          */
 /***************************************************************************/
 
-GC2_EXTERN void **GC_variable_stack;
+GC2_EXTERN THREAD_LOCAL void **GC_variable_stack;
 /*
    See the general overview in README. */
 
diff --git a/src/mzscheme/gc2/newgc.c b/src/mzscheme/gc2/newgc.c
index 3177dc6ac7..c295befc38 100644
--- a/src/mzscheme/gc2/newgc.c
+++ b/src/mzscheme/gc2/newgc.c
@@ -354,8 +354,8 @@ int GC_is_allocated(void *p)
    The size count helps us trigger collection quickly when we're running out of space; see
    the test in allocate_big. 
 */
-unsigned long GC_gen0_alloc_page_ptr = 0;
-unsigned long GC_gen0_alloc_page_end = 0;
+THREAD_LOCAL unsigned long GC_gen0_alloc_page_ptr = 0;
+THREAD_LOCAL unsigned long GC_gen0_alloc_page_end = 0;
 
 /* miscellaneous variables */
 static const char *zero_sized[4]; /* all 0-sized allocs get this */
@@ -888,7 +888,7 @@ static void *get_backtrace(struct mpage *page, void *ptr)
 /* With the exception of the "traverse" macro and resultant simplification,  */
 /* this code is entirely lifted from compact.c                               */
 /*****************************************************************************/
-void **GC_variable_stack;
+THREAD_LOCAL void **GC_variable_stack;
 
 void **GC_get_variable_stack()
 { 
@@ -1155,7 +1155,7 @@ typedef struct MarkSegment {
   void **stop_here; /* this is only used for its address */
 } MarkSegment;
 
-static MarkSegment *mark_stack = NULL;
+static THREAD_LOCAL MarkSegment *mark_stack = NULL;
 
 inline static MarkSegment* mark_stack_create_frame() {
   MarkSegment *mark_frame = (MarkSegment*)malloc(STACK_PART_SIZE);
@@ -1188,7 +1188,7 @@ inline static void push_ptr(void *ptr)
     }
   }
 
-  /* at this point, we're guaranteed to be good to push a  pointers */
+  /* at this point, we're guaranteed to be good to push pointers */
   *(mark_stack->top++) = ptr;
 }
 
@@ -1199,8 +1199,7 @@ inline static int pop_ptr(void **ptr)
       /* if there is a previous page, go to it */
       mark_stack = mark_stack->prev;
     } else {
-      /* if there isn't a previous page, then we've hit the bottom of the
-	 stack */
+      /* if there isn't a previous page, then we've hit the bottom of the stack */
       return 0;
     }
   }
@@ -2497,16 +2496,15 @@ static void garbage_collect(int force_full)
 
     while(gc->run_queue) {
       struct finalizer *f;
-      void **gcs;
+      void **saved_gc_variable_stack;
 
       f = gc->run_queue; gc->run_queue = gc->run_queue->next;
       if(!gc->run_queue) gc->last_in_queue = NULL;
 
-      GCDEBUG((DEBUGOUTF, "Running finalizers %p for pointer %p (lvl %i)\n",
-	       f, f->p, f->eager_level));
-      gcs = GC_variable_stack;
+      GCDEBUG((DEBUGOUTF, "Running finalizers %p for pointer %p (lvl %i)\n", f, f->p, f->eager_level));
+      saved_gc_variable_stack = GC_variable_stack;
       f->f(f->p, f->data);
-      GC_variable_stack = gcs;
+      GC_variable_stack = saved_gc_variable_stack;
     }
     run_account_hooks();
     running_finalizers = 0;
diff --git a/src/mzscheme/gc2/newgc_internal.h b/src/mzscheme/gc2/newgc_internal.h
index f155453416..7446bb1fe6 100644
--- a/src/mzscheme/gc2/newgc_internal.h
+++ b/src/mzscheme/gc2/newgc_internal.h
@@ -66,7 +66,6 @@ typedef struct Gen0 {
  struct mpage *curr_alloc_page;
  struct mpage *pages;
  struct mpage *big_pages;
- unsigned long GC_gen0_alloc_page_ptr;
  unsigned long current_size;
  unsigned long max_size;
 } Gen0;
diff --git a/src/mzscheme/gc2/platforms.h b/src/mzscheme/gc2/platforms.h
index 23d04884a2..6b91d5cb10 100644
--- a/src/mzscheme/gc2/platforms.h
+++ b/src/mzscheme/gc2/platforms.h
@@ -21,3 +21,14 @@
 #ifndef GC_ALIGN_EIGHT
 # define GC_ALIGN_EIGHT
 #endif
+
+#ifdef MZ_USE_PLACES
+# if _MSC_VER
+#  define THREAD_LOCAL __declspec(thread)
+# else
+#  define THREAD_LOCAL __thread
+# endif
+#else
+# define THREAD_LOCAL /* empty */
+#endif
+
diff --git a/src/mzscheme/src/jit.c b/src/mzscheme/src/jit.c
index d856e88225..bd51198ad4 100644
--- a/src/mzscheme/src/jit.c
+++ b/src/mzscheme/src/jit.c
@@ -1094,7 +1094,7 @@ static void _jit_prolog_again(mz_jit_state *jitter, int n, int ret_addr_reg)
 #endif
 
 #ifdef CAN_INLINE_ALLOC
-extern unsigned long GC_gen0_alloc_page_ptr;
+extern THREAD_LOCAL unsigned long GC_gen0_alloc_page_ptr;
 long GC_initial_word(int sizeb);
 long GC_compute_alloc_size(long sizeb);
 long GC_alloc_alignment(void);
diff --git a/src/mzscheme/src/schemef.h b/src/mzscheme/src/schemef.h
index bae0ff0fc0..f77bb5417b 100644
--- a/src/mzscheme/src/schemef.h
+++ b/src/mzscheme/src/schemef.h
@@ -399,7 +399,7 @@ MZ_EXTERN void scheme_gc_ptr_ok(void *p);
 MZ_EXTERN void scheme_collect_garbage(void);
 
 #ifdef MZ_PRECISE_GC
-MZ_EXTERN void **GC_variable_stack;
+MZ_EXTERN THREAD_LOCAL void **GC_variable_stack;
 MZ_EXTERN void GC_register_traversers(short tag, Size_Proc size, Mark_Proc mark, Fixup_Proc fixup,
 				      int is_constant_size, int is_atomic);
 MZ_EXTERN void *GC_resolve(void *p);