diff --git a/usr.bin/make/nonints.h b/usr.bin/make/nonints.h
index ad1e46d5509..24e629b1e57 100644
--- a/usr.bin/make/nonints.h
+++ b/usr.bin/make/nonints.h
@@ -95,7 +95,7 @@ Lst Parse_MainName(void);
 /* str.c */
 void str_init(void);
 void str_end(void);
-char *str_concat(const char *, const char *, int);
+char *str_concat(char *, char *, int);
 char **brk_string(char *, int *, Boolean);
 char *Str_FindSubstring(char *, char *);
 int Str_Match(char *, char *);
diff --git a/usr.bin/make/str.c b/usr.bin/make/str.c
index 1b144266721..04757591783 100644
--- a/usr.bin/make/str.c
+++ b/usr.bin/make/str.c
@@ -87,7 +87,7 @@ str_end()
  */
 char *
 str_concat(s1, s2, flags)
-	const char *s1, *s2;
+	char *s1, *s2;
 	int flags;
 {
 	int len1, len2;
@@ -117,8 +117,8 @@ str_concat(s1, s2, flags)
 
 	/* free original strings */
 	if (flags & STR_DOFREE) {
-		(void)efree((void *)s1);
-		(void)efree((void *)s2);
+		(void)efree(s1);
+		(void)efree(s2);
 	}
 	return(result);
 }