diff --git a/ueforth/Makefile b/ueforth/Makefile
index dd121b8..896ac97 100644
--- a/ueforth/Makefile
+++ b/ueforth/Makefile
@@ -361,7 +361,7 @@ $(ESP32_SIM)/Esp32forth-sim: \
     common/interp.h \
     $(GEN)/esp32_boot.h \
     $(GEN)/esp32_sim_opcodes.h | $(ESP32_SIM)
-	$(CXX) $(CFLAGS) -m32 $< -o $@
+	$(CXX) $(CFLAGS) -m32 -D_FILE_OFFSET_BITS=64 $< -o $@
 	strip $(STRIP_ARGS) $@
 
 sizes: $(ESP32_SIM)/Esp32forth-sim
diff --git a/ueforth/common/core.h b/ueforth/common/core.h
index f944e90..ce879e3 100644
--- a/ueforth/common/core.h
+++ b/ueforth/common/core.h
@@ -125,7 +125,9 @@ static cell_t find(const char *name, cell_t len) {
 
 static void create(const char *name, cell_t nlength, cell_t flags, void *op) {
   if (g_sys.latestxt) {
-    g_sys.latestxt[-1] |= ((g_sys.heap - &g_sys.latestxt[1]) << 16);
+    cell_t sz = g_sys.heap - &g_sys.latestxt[1];
+    if (sz < 0 || sz > 0xffff) { sz = 0xffff; }
+    g_sys.latestxt[-1] |= (sz << 16);
   }
   g_sys.heap = (cell_t *) CELL_ALIGNED(g_sys.heap);
   char *pos = (char *) g_sys.heap;