diff --git a/edit/edit.c b/edit/edit.c
index cb262e258..f89d61e3d 100644
--- a/edit/edit.c
+++ b/edit/edit.c
@@ -513,7 +513,7 @@ edit_init (WEdit *edit, int lines, int columns, const char *filename,
 		    option_whole_chars_search);
 
 	    for (i = 1; i <= sizeof (option_whole_chars_search_buf); i++) {
-		if (islower (i) && !strchr (option_whole_chars_search, i)) {
+		if (g_ascii_islower ((gchar) i) && !strchr (option_whole_chars_search, i)) {
 		    option_whole_chars_search_buf[len++] = i;
 		}
 	    }
@@ -1687,7 +1687,7 @@ my_type_of (int c)
     }
     if (isupper (c))
 	c = 'A';
-    else if (islower (c))
+    else if (g_ascii_islower ((gchar) c))
 	c = 'a';
     else if (g_ascii_isalpha (c))
 	c = 'a';
diff --git a/edit/editcmd.c b/edit/editcmd.c
index dd4154ac8..c0004eb8c 100644
--- a/edit/editcmd.c
+++ b/edit/editcmd.c
@@ -90,7 +90,7 @@ static unsigned char *edit_get_block (WEdit *edit, long start,
 
 static inline int my_lower_case (int c)
 {
-    return tolower(c & 0xFF);
+    return g_ascii_tolower ((gchar)c & 0xFF);
 }
 
 static const char *