diff --git a/ext/etc/etc.c b/ext/etc/etc.c
index 4cd941f586..c355fe117a 100644
--- a/ext/etc/etc.c
+++ b/ext/etc/etc.c
@@ -47,8 +47,12 @@ static VALUE sGroup;
 #define HAVE_UNAME 1
 #endif
 
-#ifndef _WIN32
-char *getenv();
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
 #endif
 char *getlogin();
 
diff --git a/ext/pty/pty.c b/ext/pty/pty.c
index 155d215942..acec33f9bf 100644
--- a/ext/pty/pty.c
+++ b/ext/pty/pty.c
@@ -170,7 +170,7 @@ establishShell(int argc, VALUE *argv, struct pty_info *info,
 {
     int 		master, slave, status = 0;
     rb_pid_t		pid;
-    char		*p, *getenv();
+    char		*p;
     VALUE		v;
     struct child_info   carg;
     char		errbuf[32];