diff --git a/radio/src/lv_conf.h b/radio/src/lv_conf.h
index 86468e5f4b6..1b2174c6dd8 100644
--- a/radio/src/lv_conf.h
+++ b/radio/src/lv_conf.h
@@ -61,7 +61,7 @@
     #if LV_MEM_ADR == 0
         //#define LV_MEM_POOL_INCLUDE your_alloc_library  /* Uncomment if using an external allocator*/
         //#define LV_MEM_POOL_ALLOC   your_alloc          /* Uncomment if using an external allocator*/
-        extern void *sbrk(int size);
+        #define LV_MEM_POOL_INCLUDE <unistd.h>
         #define LV_MEM_POOL_ALLOC sbrk
     #endif