diff --git a/uefi/crt_aarch64.c b/uefi/crt_aarch64.c
index e4c6d9e..ef0db22 100644
--- a/uefi/crt_aarch64.c
+++ b/uefi/crt_aarch64.c
@@ -69,7 +69,7 @@ char *__argvutf8 = NULL;
 #endif
 
 /* we only need one .o file, so use inline Assembly here */
-void bootstrap()
+void bootstrap(void)
 {
     __asm__ __volatile__ (
     /* call init in C */
diff --git a/uefi/crt_x86_64.c b/uefi/crt_x86_64.c
index b7c58b3..4151e67 100644
--- a/uefi/crt_x86_64.c
+++ b/uefi/crt_x86_64.c
@@ -69,7 +69,7 @@ char *__argvutf8 = NULL;
 #endif
 
 /* we only need one .o file, so use inline Assembly here */
-void bootstrap()
+void bootstrap(void)
 {
     __asm__ __volatile__ (
     /* call init in C */
diff --git a/uefi/uefi.h b/uefi/uefi.h
index 423768b..6f900ed 100644
--- a/uefi/uefi.h
+++ b/uefi/uefi.h
@@ -1300,7 +1300,7 @@ extern void free (void *__ptr);
 extern void abort (void);
 extern void exit (int __status);
 /* exit Boot Services function. Returns 0 on success. */
-extern int exit_bs();
+extern int exit_bs(void);
 extern void *bsearch (const void *__key, const void *__base, size_t __nmemb, size_t __size, __compar_fn_t __compar);
 extern void qsort (void *__base, size_t __nmemb, size_t __size, __compar_fn_t __compar);
 extern int mblen (const char *__s, size_t __n);