diff --git a/src/chars.c b/src/chars.c
index 81536e37..23fbba49 100644
--- a/src/chars.c
+++ b/src/chars.c
@@ -56,12 +56,6 @@ char *addstrings(char* str1, size_t len1, char* str2, size_t len2)
 	return str1;
 }
 
-/* Return TRUE if the value of c is in byte range, and FALSE otherwise. */
-bool is_byte(int c)
-{
-	return ((unsigned int)c == (unsigned char)c);
-}
-
 /* This function is equivalent to isalpha() for multibyte characters. */
 bool is_alpha_mbchar(const char *c)
 {
@@ -110,13 +104,6 @@ bool is_blank_mbchar(const char *c)
 		return isblank((unsigned char)*c);
 }
 
-/* This function is equivalent to iscntrl(), except in that it only
- * handles non-high-bit control characters. */
-bool is_ascii_cntrl_char(int c)
-{
-	return (0 <= c && c < 32);
-}
-
 /* This function is equivalent to iscntrl() for multibyte characters,
  * except in that it also handles multibyte control characters with
  * their high bits set. */
diff --git a/src/nano.c b/src/nano.c
index 436a6262..91962adc 100644
--- a/src/nano.c
+++ b/src/nano.c
@@ -1531,7 +1531,7 @@ void do_input(void)
 	/* If we got a non-high-bit control key, a meta key sequence, or a
 	 * function key, and it's not a shortcut or toggle, throw it out. */
 	if (shortcut == NULL) {
-		if (is_ascii_cntrl_char(input) || meta_key || !is_byte(input)) {
+		if (input < 0x20 || input > 0xFF || meta_key) {
 			unbound_key(input);
 			input = ERR;
 		}
diff --git a/src/prompt.c b/src/prompt.c
index f872038e..d863d5fd 100644
--- a/src/prompt.c
+++ b/src/prompt.c
@@ -90,7 +90,7 @@ int do_statusbar_input(bool *finished)
 	/* If we got a non-high-bit control key, a meta key sequence, or a
 	 * function key, and it's not a shortcut or toggle, throw it out. */
 	if (shortcut == NULL) {
-		if (is_ascii_cntrl_char(input) || meta_key || !is_byte(input)) {
+		if (input < 0x20 || input > 0xFF || meta_key) {
 			beep();
 			input = ERR;
 		}
diff --git a/src/proto.h b/src/proto.h
index 30449d27..dfb3d7f6 100644
--- a/src/proto.h
+++ b/src/proto.h
@@ -204,10 +204,8 @@ void utf8_init(void);
 bool using_utf8(void);
 #endif
 char *addstrings(char* str1, size_t len1, char* str2, size_t len2);
-bool is_byte(int c);
 bool is_alpha_mbchar(const char *c);
 bool is_blank_mbchar(const char *c);
-bool is_ascii_cntrl_char(int c);
 bool is_cntrl_mbchar(const char *c);
 bool is_word_mbchar(const char *c, bool allow_punct);
 char control_mbrep(const char *c, bool isdata);