diff --git a/extmod/modTrezorUi/modTrezorUi-inflate.h b/extmod/modTrezorUi/modTrezorUi-inflate.h
index ad8d0ad46e..a57a0c9ac1 100644
--- a/extmod/modTrezorUi/modTrezorUi-inflate.h
+++ b/extmod/modTrezorUi/modTrezorUi-inflate.h
@@ -36,10 +36,6 @@
 
 #include <stdint.h>
 
-#ifndef SINF_WRITE
-#error Must define SINF_WRITE(byte) macro
-#endif
-
 // maximum possible window size (in bits) used during compression/deflate
 #define SINF_WBITS     10
 
@@ -59,6 +55,7 @@ typedef struct {
    int cbufi;
    SINF_TREE ltree; /* dynamic length/symbol tree */
    SINF_TREE dtree; /* dynamic distance tree */
+   void (* write)(uint8_t byte);
 } SINF_DATA;
 
 /* --------------------------------------------------- *
@@ -106,7 +103,7 @@ static void sinf_write(SINF_DATA *d, uint8_t byte)
 {
     d->cbuf[d->cbufi] = byte;
     d->cbufi = (d->cbufi + 1) % (1 << SINF_WBITS);
-    SINF_WRITE(byte);
+    d->write(byte);
 }
 
 /* build the fixed huffman trees */
@@ -394,7 +391,7 @@ static int sinf_inflate_dynamic_block(SINF_DATA *d)
  * ---------------------- */
 
 /* inflate stream from source */
-static int sinf_inflate(uint8_t *data)
+static int sinf_inflate(uint8_t *data, void (*write_callback)(uint8_t byte))
 {
    SINF_DATA d;
    int bfinal;
@@ -403,6 +400,7 @@ static int sinf_inflate(uint8_t *data)
    d.bitcount = 0;
    d.cbufi = 0;
    d.source = data;
+   d.write = write_callback;
 
    do {
 
diff --git a/extmod/modTrezorUi/modTrezorUi-stmhal.h b/extmod/modTrezorUi/modTrezorUi-stmhal.h
index bccbb47e49..91e04bf58e 100644
--- a/extmod/modTrezorUi/modTrezorUi-stmhal.h
+++ b/extmod/modTrezorUi/modTrezorUi-stmhal.h
@@ -10,6 +10,10 @@
 #define CMD(X)  (*((__IO uint8_t *)((uint32_t)(0x60000000))) = (X))
 #define DATA(X) (*((__IO uint8_t *)((uint32_t)(0x60000000 | 0x10000))) = (X))
 
+static void DATAfunc(uint8_t x) {
+    DATA(x);
+}
+
 static void DATAS(void *bytes, int len);
 
 void sram_init(void) {
diff --git a/extmod/modTrezorUi/modTrezorUi-unix.h b/extmod/modTrezorUi/modTrezorUi-unix.h
index 482e6051f0..96a33f4138 100644
--- a/extmod/modTrezorUi/modTrezorUi-unix.h
+++ b/extmod/modTrezorUi/modTrezorUi-unix.h
@@ -14,7 +14,9 @@ static SDL_Texture  *TEXTURE  = 0;
 static int DATAODD = 0;
 static int POSX, POSY, SX, SY, EX, EY = 0;
 
-static void DATA(uint8_t x) {
+#define DATA(X) DATAfunc((X))
+
+static void DATAfunc(uint8_t x) {
     if (!SDL_inited) return;
     if (POSX <= EX && POSY <= EY) {
         ((uint8_t *)SCREEN->pixels)[POSX * 2 + POSY * SCREEN->pitch + (DATAODD ^ 1)] = x;
diff --git a/extmod/modTrezorUi/modTrezorUi.c b/extmod/modTrezorUi/modTrezorUi.c
index 084e0cf196..4aa7fe905d 100644
--- a/extmod/modTrezorUi/modTrezorUi.c
+++ b/extmod/modTrezorUi/modTrezorUi.c
@@ -60,7 +60,7 @@ static void display_blit(uint8_t x, uint8_t y, uint8_t w, uint8_t h, void *data,
 
 static void display_image(uint8_t x, uint8_t y, uint8_t w, uint8_t h, void *data, int datalen) {
     display_set_window(x, y, w, h);
-    sinf_inflate(data);
+    sinf_inflate(data, DATAfunc);
     display_update();
 }