diff --git a/appl/telnet/telnet/authenc.c b/appl/telnet/telnet/authenc.c
index 4a856c491..909ee5af2 100644
--- a/appl/telnet/telnet/authenc.c
+++ b/appl/telnet/telnet/authenc.c
@@ -66,7 +66,7 @@ telnet_spin(void)
 }
 
 char *
-telnet_getenv(char *val)
+telnet_getenv(const char *val)
 {
 	return((char *)env_getvalue((unsigned char *)val));
 }
diff --git a/appl/telnet/telnet/externs.h b/appl/telnet/telnet/externs.h
index dee8e5b3c..eb86956ce 100644
--- a/appl/telnet/telnet/externs.h
+++ b/appl/telnet/telnet/externs.h
@@ -182,7 +182,7 @@ extern jmp_buf
 int telnet_net_write(unsigned char *str, int len);
 void net_encrypt(void);
 int telnet_spin(void);
-char *telnet_getenv(char *val);
+char *telnet_getenv(const char *val);
 char *telnet_gets(char *prompt, char *result, int length, int echo);
 #endif
 
diff --git a/appl/telnet/telnetd/ext.h b/appl/telnet/telnetd/ext.h
index 4bdae6d36..c6e58c17c 100644
--- a/appl/telnet/telnetd/ext.h
+++ b/appl/telnet/telnetd/ext.h
@@ -78,7 +78,7 @@ extern int	SYNCHing;		/* we are in TELNET SYNCH mode */
 int telnet_net_write (unsigned char *str, int len);
 void net_encrypt (void);
 int telnet_spin (void);
-char *telnet_getenv (char *val);
+char *telnet_getenv (const char *val);
 char *telnet_gets (char *prompt, char *result, int length, int echo);
 void get_slc_defaults (void);
 void telrcv (void);