diff --git a/bin/sh/alias.c b/bin/sh/alias.c
index dd613515a2e8..5302b03de56d 100644
--- a/bin/sh/alias.c
+++ b/bin/sh/alias.c
@@ -144,7 +144,7 @@ unalias(char *name)
 }
 
 #ifdef mkinit
-MKINIT void rmaliases();
+MKINIT void rmaliases(void);
 
 SHELLPROC {
 	rmaliases();
diff --git a/bin/sh/exec.c b/bin/sh/exec.c
index 03c6162b8154..55e3fec543c3 100644
--- a/bin/sh/exec.c
+++ b/bin/sh/exec.c
@@ -555,7 +555,7 @@ clearcmdentry(int firstchange)
  */
 
 #ifdef mkinit
-MKINIT void deletefuncs();
+MKINIT void deletefuncs(void);
 
 SHELLPROC {
 	deletefuncs();
diff --git a/bin/sh/var.c b/bin/sh/var.c
index 94d6feeb3ccb..7a77ee2ab02b 100644
--- a/bin/sh/var.c
+++ b/bin/sh/var.c
@@ -445,7 +445,7 @@ environment(void)
  */
 
 #ifdef mkinit
-MKINIT void shprocvar();
+MKINIT void shprocvar(void);
 
 SHELLPROC {
 	shprocvar();