diff --git a/src/bookmarks/backend/xbel.c b/src/bookmarks/backend/xbel.c
index 25ef2cbd6..f7042792c 100644
--- a/src/bookmarks/backend/xbel.c
+++ b/src/bookmarks/backend/xbel.c
@@ -195,7 +195,7 @@ print_xml_entities(struct secure_save_info *ssi, const unsigned char *str)
 				secure_fprintf(ssi, "&#%i;", (int) *str);
 			}
 			else {
-				unsigned char *s = u2cp_no_nbsp(*str, cp);
+				const unsigned char *s = u2cp_no_nbsp(*str, cp);
 
 				if (s) print_xml_entities(ssi, s);
 			}
diff --git a/src/intl/charsets.c b/src/intl/charsets.c
index 4e13819d1..c8f350d9d 100644
--- a/src/intl/charsets.c
+++ b/src/intl/charsets.c
@@ -168,7 +168,7 @@ static const unicode_val_T strange_chars[32] = {
 #define SYSTEM_CHARSET_FLAG 128
 #define is_cp_ptr_utf8(cp_ptr) ((cp_ptr)->aliases == aliases_utf8)
 
-unsigned char *
+const unsigned char *
 u2cp_(unicode_val_T u, int to, enum nbsp_mode nbsp_mode)
 {
 	int j;
@@ -928,7 +928,7 @@ get_translation_table(int from, int to)
 
 		for (i = 128; i < 256; i++) {
 			if (codepages[from].highhalf[i - 0x80] != 0xFFFF) {
-				unsigned char *u;
+				const unsigned char *u;
 
 				u = u2cp(codepages[from].highhalf[i - 0x80], to);
 				if (u) table[i].u.str = u;
diff --git a/src/intl/charsets.h b/src/intl/charsets.h
index db123a240..bee9d14e5 100644
--- a/src/intl/charsets.h
+++ b/src/intl/charsets.h
@@ -138,7 +138,7 @@ unicode_val_T cp_to_unicode(int, unsigned char **, unsigned char *);
 unicode_val_T cp2u(int, unsigned char);
 unsigned char *cp2utf8(int, int);
 
-unsigned char *u2cp_(unicode_val_T, int, enum nbsp_mode);
+const unsigned char *u2cp_(unicode_val_T, int, enum nbsp_mode);
 #define u2cp(u, to) u2cp_(u, to, NBSP_MODE_HACK)
 #define u2cp_no_nbsp(u, to) u2cp_(u, to, NBSP_MODE_ASCII)
 
diff --git a/src/terminal/event.c b/src/terminal/event.c
index 49913aaba..6d5dc40c7 100644
--- a/src/terminal/event.c
+++ b/src/terminal/event.c
@@ -143,7 +143,7 @@ term_send_ucs(struct terminal *term, unicode_val_T u,
 	term_send_event(term, &ev);
 #else  /* !CONFIG_UTF8 */
 	struct term_event ev;
-	unsigned char *recoded;
+	const unsigned char *recoded;
 
 	set_kbd_term_event(&ev, KBD_UNDEF, modifier);
 	recoded = u2cp_no_nbsp(u, get_opt_codepage_tree(term->spec, "charset"));
diff --git a/src/viewer/text/form.c b/src/viewer/text/form.c
index 83d904f4f..483931f68 100644
--- a/src/viewer/text/form.c
+++ b/src/viewer/text/form.c
@@ -1355,6 +1355,7 @@ field_op(struct session *ses, struct document_view *doc_view,
 	struct form_state *fs;
 	enum edit_action action_id;
 	unsigned char *text;
+	const unsigned char *ctext;
 	int length;
 	enum frame_event_status status = FRAME_EVENT_REFRESH;
 #ifdef CONFIG_UTF8
@@ -1748,19 +1749,19 @@ field_op(struct session *ses, struct document_view *doc_view,
 			if (ses->tab->term->utf8) {
 				/* fs->value is in UTF-8 regardless of
 				 * the charset of the terminal.  */
-				text = encode_utf8(get_kbd_key(ev));
+				ctext = encode_utf8(get_kbd_key(ev));
 			} else {
 				/* fs->value is in the charset of the
 				 * terminal.  */
 				int cp = get_opt_codepage_tree(ses->tab->term->spec,
 							       "charset");
 
-				text = u2cp_no_nbsp(get_kbd_key(ev), cp);
+				ctext = u2cp_no_nbsp(get_kbd_key(ev), cp);
 			}
-			length = strlen(text);
+			length = strlen(ctext);
 
 			if (strlen(fs->value) + length > fc->maxlength
-			    || !insert_in_string(&fs->value, fs->state, text, length)) {
+			    || !insert_in_string(&fs->value, fs->state, ctext, length)) {
 				status = FRAME_EVENT_OK;
 				break;
 			}