diff --git a/firmware/libc/include/stdio.h b/firmware/libc/include/stdio.h
index d9a6dce55f..14f531fad1 100644
--- a/firmware/libc/include/stdio.h
+++ b/firmware/libc/include/stdio.h
@@ -40,11 +40,6 @@ int sprintf  (char *buf, const char *fmt, ...) ATTRIBUTE_PRINTF(2, 3);
 int snprintf (char *buf, size_t size, const char *fmt, ...)
               ATTRIBUTE_PRINTF(3, 4);
 
-/* callback function is called for every output character (byte) with userp and
- * should return 0 when ch is a char other than '\0' that should stop printing */
-int vuprintf(int (*push)(void *userp, unsigned char data),
-              void *userp, const char *fmt, __VALIST ap);
-
 int sscanf(const char *s, const char *fmt, ...)
     ATTRIBUTE_SCANF(2, 3);
 
diff --git a/firmware/logf.c b/firmware/logf.c
index b68f8a1d26..6bdda3f424 100644
--- a/firmware/logf.c
+++ b/firmware/logf.c
@@ -35,6 +35,7 @@
 #include "lcd-remote.h"
 #include "logf.h"
 #include "serial.h"
+#include "format.h"
 
 #ifdef HAVE_USBSTACK
 #include "usb_core.h"
diff --git a/firmware/target/arm/s3c2440/uart-s3c2440.c b/firmware/target/arm/s3c2440/uart-s3c2440.c
index 829eb05270..8fe6511253 100644
--- a/firmware/target/arm/s3c2440/uart-s3c2440.c
+++ b/firmware/target/arm/s3c2440/uart-s3c2440.c
@@ -29,6 +29,7 @@
 #include "system.h"
 #include "kernel.h"
 #include "thread.h"
+#include "format.h"
 
 #include "system-target.h"
 #include "uart-s3c2440.h"