diff --git a/lib/n64graphics/n64graphics.c b/lib/n64graphics/n64graphics.c
index 78842e4..5d29305 100644
--- a/lib/n64graphics/n64graphics.c
+++ b/lib/n64graphics/n64graphics.c
@@ -10,6 +10,10 @@
 #define STBI_NO_HDR
 #define STBI_NO_TGA
 #include <stb_image.h>
+// intern function
+extern unsigned char *stbi_write_png_to_mem(const unsigned char *pixels, int stride_bytes, int x, int y, int n, int *out_len);
+extern unsigned char *stbi_write_plte_png_to_mem(const unsigned char *pixels, int stride_bytes, int x, int y, int n, pixel* plte, int plte_size, int *out_len);
+
 #include <stb_image_write.h>
 
 #include "n64graphics.h"