diff --git a/litex/soc/software/demo/donut.c b/litex/soc/software/demo/donut.c
index 0aab4177e..eab0905dc 100644
--- a/litex/soc/software/demo/donut.c
+++ b/litex/soc/software/demo/donut.c
@@ -21,6 +21,7 @@
 
 signed char b[1760], z[1760];
 
+void donut(void);
 void donut(void) {
   int sA=1024,cA=0,sB=1024,cB=0,_;
   for (;;) {
diff --git a/litex/soc/software/demo/helloc.c b/litex/soc/software/demo/helloc.c
index 6549e1262..e8750cc83 100644
--- a/litex/soc/software/demo/helloc.c
+++ b/litex/soc/software/demo/helloc.c
@@ -1,5 +1,6 @@
 #include <stdio.h>
 
+void helloc(void);
 void helloc(void) {
   printf("C: Hello, world!\n");
 }
\ No newline at end of file