diff --git a/litex/soc/software/libc/missing.c b/litex/soc/software/libc/missing.c
index c70d8f368..fb9faf22e 100644
--- a/litex/soc/software/libc/missing.c
+++ b/litex/soc/software/libc/missing.c
@@ -5,6 +5,7 @@
  */
 
 #include <stddef.h>
+#include <errno.h>
 
 int getentropy(void *v, size_t s) {
     return -1;