diff --git a/build.zig b/build.zig
index cc283bc..ed397e8 100644
--- a/build.zig
+++ b/build.zig
@@ -54,7 +54,7 @@ pub fn build(b: *std.build.Builder) void {
     ngui.defineCMacroRaw(b.fmt("NM_DISP_VER={}", .{disp_vert}));
     ngui.defineCMacro("LV_CONF_INCLUDE_SIMPLE", null);
     ngui.defineCMacro("LV_TICK_CUSTOM", "1");
-    ngui.defineCMacro("LV_TICK_CUSTOM_INCLUDE", "\"ui.h\"");
+    ngui.defineCMacro("LV_TICK_CUSTOM_INCLUDE", "\"lv_custom_tick.h\"");
     ngui.defineCMacro("LV_TICK_CUSTOM_SYS_TIME_EXPR", "(nm_get_curr_tick())");
     switch (drv) {
         .sdl2 => {
diff --git a/src/ui/c/lv_custom_tick.h b/src/ui/c/lv_custom_tick.h
new file mode 100644
index 0000000..77ed9fb
--- /dev/null
+++ b/src/ui/c/lv_custom_tick.h
@@ -0,0 +1,16 @@
+#ifndef NM_UI_H
+#define NM_UI_H
+
+/**
+ * this file exists to satisfy LV_TICK_CUSTOM_INCLUDE.
+ */
+
+#include <stdint.h>
+
+/**
+ * returns elapsed time since program start, in ms.
+ * rolls over when overflow occurs.
+ */
+uint32_t nm_get_curr_tick();
+
+#endif
diff --git a/src/ui/c/ui.c b/src/ui/c/ui.c
index e0d8599..e72724d 100644
--- a/src/ui/c/ui.c
+++ b/src/ui/c/ui.c
@@ -1,12 +1,31 @@
+/**
+ * function declarations with nm_ prefix are typically defined in zig,
+ * while extern'ed function definitions with nm_ prefix are typically called from zig.
+ */
+
 #define _DEFAULT_SOURCE /* needed for usleep() */
 
 #include "lvgl/lvgl.h"
 
-#include "ui.h"
-
 #include <stdlib.h>
 #include <unistd.h>
 
+/**
+ * initiates system shutdown leading to poweroff.
+ */
+void nm_sys_shutdown();
+
+/**
+ * invoken when the UI is switched to the network settings tab.
+ */
+void nm_tab_settings_active();
+
+/**
+ * initiate connection to a wifi network with the given SSID and a password.
+ * connection, if successful, is persisted in wpa_supplicant config.
+ */
+int nm_wifi_start_connect(const char *ssid, const char *password);
+
 static lv_style_t style_title;
 static lv_style_t style_text_muted;
 static lv_style_t style_btn_red;
diff --git a/src/ui/c/ui.h b/src/ui/c/ui.h
deleted file mode 100644
index 1029657..0000000
--- a/src/ui/c/ui.h
+++ /dev/null
@@ -1,28 +0,0 @@
-#ifndef NM_UI_H
-#define NM_UI_H
-
-#include <stdint.h>
-
-/**
- * returns elapsed time since program start, in ms.
- * rolls over when overflow occurs.
- */
-uint32_t nm_get_curr_tick();
-
-/**
- * initiates system shutdown leading to poweroff.
- */
-void nm_sys_shutdown();
-
-/**
- * invoken when the UI is switched to the network settings tab.
- */
-void nm_tab_settings_active();
-
-/**
- * initiate connection to a wifi network with the given SSID and a password.
- * connection, if successful, is persisted in wpa_supplicant config.
- */
-int nm_wifi_start_connect(const char *ssid, const char *password);
-
-#endif