diff --git a/c_mpos/mpong/Makefile b/c_mpos/mpong/Makefile
index 2538a7d3..2b45c47b 100644
--- a/c_mpos/mpong/Makefile
+++ b/c_mpos/mpong/Makefile
@@ -6,6 +6,9 @@ MOD = mpong
 # Source files (.c or .py)
 SRC = mpong.c
 
+# Link runtime libraries (needed for memset on xtensawin)
+LINK_RUNTIME = 1
+
 # Architectures to build for (x86, x64, armv6m, armv7m, xtensa, xtensawin, rv32imc, rv64imc)
 ARCHES = x64 xtensawin
 
diff --git a/c_mpos/mpong/build.sh b/c_mpos/mpong/build.sh
index c811b113..3f3115fb 100755
--- a/c_mpos/mpong/build.sh
+++ b/c_mpos/mpong/build.sh
@@ -1,4 +1,4 @@
-#. /home/user/projects/MicroPythonOS/claude/.espressif/python_env/idf5.4_py3.11_env/bin/activate
+. ~/.espressif/python_env/idf5.4_py3.11_env/bin/activate
 
 mydir=$(readlink -f "$0")
 mydir=$(dirname "$mydir")
@@ -10,4 +10,4 @@ rm *.mpy
 
 PATH=~/.espressif/tools/xtensa-esp-elf/esp-14.2.0_20241119/xtensa-esp-elf/bin/:$PATH make </dev/null
 
-mv mpong*.mpy ../../internal_filesystem/apps/com.micropythonos.mpong/assets/
+mv mpong*.mpy "$mydir"/../../internal_filesystem/apps/com.micropythonos.mpong/assets/
diff --git a/c_mpos/mpong/mpong.c b/c_mpos/mpong/mpong.c
index 600feb6f..5beeb8ab 100644
--- a/c_mpos/mpong/mpong.c
+++ b/c_mpos/mpong/mpong.c
@@ -1,6 +1,15 @@
 // Include the header file to get access to the MicroPython API
 #include "py/dynruntime.h"
 
+// Provide a local memset for xtensawin native modules (libc isn't linked).
+void *memset(void *s, int c, size_t n) {
+    unsigned char *p = (unsigned char *)s;
+    while (n--) {
+        *p++ = (unsigned char)c;
+    }
+    return s;
+}
+
 // Global BSS (non-static) state is required for native modules.
 uint16_t *g_framebuffer;
 size_t g_framebuffer_len;
diff --git a/internal_filesystem/apps/com.micropythonos.mpong/assets/mpong.py b/internal_filesystem/apps/com.micropythonos.mpong/assets/mpong.py
index 8e6a3b7c..c34205e7 100644
--- a/internal_filesystem/apps/com.micropythonos.mpong/assets/mpong.py
+++ b/internal_filesystem/apps/com.micropythonos.mpong/assets/mpong.py
@@ -65,7 +65,7 @@ class MPong(Activity):
     def onResume(self, screen):
         lv.log_register_print_cb(self.log_callback)
         mpong.init(self.buffer, self.hor_res, self.ver_res)
-        self.refresh_timer = lv.timer_create(self.run_mpong, 15, None)
+        self.refresh_timer = lv.timer_create(self.run_mpong, 30, None)
 
     def onPause(self, screen):
         if self.refresh_timer:
@@ -97,7 +97,7 @@ class MPong(Activity):
         focused = focusgroup.get_focused()
         if focused:
             #print(f"got focus button: {focused}")
-            label = focused.get_child(0)
+            #label = focused.get_child(0)
             #print(f"got label for button: {label.get_text()}")
             #focused.remove_state(lv.STATE.FOCUSED) # this doesn't seem to work to remove focus
             #print("checking which button is focused")
@@ -114,6 +114,7 @@ class MPong(Activity):
     def run_mpong(self, timer=None):
         mpong.render()
         self.canvas.invalidate() # force redraw
+        self.canvas.center()
 
     def touch_cb(self, event):
         event_code = event.get_code()