diff --git a/ueforth/common/core.h b/ueforth/common/core.h
index ad24705..bfe0c4d 100644
--- a/ueforth/common/core.h
+++ b/ueforth/common/core.h
@@ -190,11 +190,11 @@ static cell_t *evaluate1(cell_t *sp, float **fp) {
 static cell_t *forth_run(cell_t *initrp);
 
 static void forth_init(int argc, char *argv[], void *heap,
-                         const char *src, cell_t src_len) {
+                       const char *src, cell_t src_len) {
   g_sys.heap = ((cell_t *) heap) + 4;  // Leave a little room.
-  cell_t *sp = g_sys.heap + 1; g_sys.heap += STACK_SIZE;
-  cell_t *rp = g_sys.heap + 1; g_sys.heap += STACK_SIZE;
   float *fp = (float *) (g_sys.heap + 1); g_sys.heap += STACK_SIZE;
+  cell_t *rp = g_sys.heap + 1; g_sys.heap += STACK_SIZE;
+  cell_t *sp = g_sys.heap + 1; g_sys.heap += STACK_SIZE;
 
   // FORTH vocabulary
   *g_sys.heap++ = 0; cell_t *forth = g_sys.heap;
@@ -221,8 +221,8 @@ static void forth_init(int argc, char *argv[], void *heap,
   g_sys.base = 10;
   g_sys.tib = src;
   g_sys.ntib = src_len;
-  *++rp = (cell_t) sp;
   *++rp = (cell_t) fp;
+  *++rp = (cell_t) sp;
   *++rp = (cell_t) start;
   g_sys.rp = rp;
   g_sys.runner = forth_run;
diff --git a/ueforth/common/interp.h b/ueforth/common/interp.h
index bb07d48..09c2131 100644
--- a/ueforth/common/interp.h
+++ b/ueforth/common/interp.h
@@ -28,9 +28,7 @@ static cell_t *forth_run(cell_t *init_rp) {
   }
   register cell_t *ip, *rp, *sp, tos, w;
   register float *fp;
-  rp = init_rp;  ip = (cell_t *) *rp--;  sp = (cell_t *) *rp--;
-  fp = (float *) *rp--;
-  DROP; NEXT;
+  rp = init_rp; UNPARK; NEXT;
 #define X(name, op, code) OP_ ## op: { code; } NEXT;
   PLATFORM_OPCODE_LIST
   OPCODE_LIST
diff --git a/ueforth/common/opcodes.h b/ueforth/common/opcodes.h
index 2bf8693..bf215d7 100644
--- a/ueforth/common/opcodes.h
+++ b/ueforth/common/opcodes.h
@@ -31,7 +31,9 @@ typedef uintptr_t ucell_t;
 #define DOIMMEDIATE() (*g_sys.current)[-1] |= IMMEDIATE
 #define UNSMUDGE() (*g_sys.current)[-1] &= ~SMUDGE
 #define DOES(ip) **g_sys.current = (cell_t) ADDR_DODOES; (*g_sys.current)[1] = (cell_t) ip
-#define PARK DUP; *++rp = (cell_t) fp; *++rp = (cell_t) sp; *++rp = (cell_t) ip
+
+#define PARK   DUP; *++rp = (cell_t) fp; *++rp = (cell_t) sp; *++rp = (cell_t) ip
+#define UNPARK ip = (cell_t *) *rp--;  sp = (cell_t *) *rp--; fp = (float *) *rp--; DROP
 
 #ifndef SSMOD_FUNC
 # if __SIZEOF_POINTER__ == 8
diff --git a/ueforth/esp32/template.ino b/ueforth/esp32/template.ino
index 074444b..712a7d6 100644
--- a/ueforth/esp32/template.ino
+++ b/ueforth/esp32/template.ino
@@ -599,9 +599,11 @@ static void InvokeWebServerOn(WebServer *ws, const char *url, cell_t xt) {
     cell_t code[2];
     code[0] = xt;
     code[1] = g_sys.YIELD_XT;
-    cell_t stack[INTERRUPT_STACK_CELLS];
+    cell_t fstack[INTERRUPT_STACK_CELLS];
     cell_t rstack[INTERRUPT_STACK_CELLS];
+    cell_t stack[INTERRUPT_STACK_CELLS];
     cell_t *rp = rstack;
+    *++rp = (cell_t) (fstack + 1);
     *++rp = (cell_t) (stack + 1);
     *++rp = (cell_t) code;
     forth_run(rp);
@@ -620,10 +622,12 @@ static void IRAM_ATTR HandleInterrupt(void *arg) {
   cell_t code[2];
   code[0] = args->xt;
   code[1] = g_sys.YIELD_XT;
-  cell_t stack[INTERRUPT_STACK_CELLS];
+  cell_t fstack[INTERRUPT_STACK_CELLS];
   cell_t rstack[INTERRUPT_STACK_CELLS];
+  cell_t stack[INTERRUPT_STACK_CELLS];
   stack[0] = args->arg;
   cell_t *rp = rstack;
+  *++rp = (cell_t) (fstack + 1);
   *++rp = (cell_t) (stack + 1);
   *++rp = (cell_t) code;
   forth_run(rp);
diff --git a/ueforth/windows/windows_interp.h b/ueforth/windows/windows_interp.h
index 0a7d84b..08b61a7 100644
--- a/ueforth/windows/windows_interp.h
+++ b/ueforth/windows/windows_interp.h
@@ -39,9 +39,7 @@ static cell_t *forth_run(cell_t *init_rp) {
   }
   register cell_t *ip, *rp, *sp, tos, w;
   register float *fp;
-  rp = init_rp;  ip = (cell_t *) *rp--;  sp = (cell_t *) *rp--;
-  fp = (float *) *rp--;
-  DROP;
+  rp = init_rp; UNPARK;
   for (;;) {
 next:
     w = *ip++;