FROM: https://github.com/Orc/discount/issues/283
FROM: Atri Bhattacharya <badshah400@gmail.com>

--- a/main.c
+++ b/main.c
@@ -100,14 +100,15 @@ free_it(char *object, void *ctx)
 }
 
 char *
-external_codefmt(char *src, int len, char *lang)
+external_codefmt(const char *src, const int len, void *lang)
 {
     int extra = 0;
     int i, x;
     char *res;
+    char *ec_lang = (char *)lang;
 
-    if ( lang == 0 )
-	lang = "generic_code";
+    if ( ec_lang == 0 )
+	ec_lang = "generic_code";
 
     for ( i=0; i < len; i++) {
 	if ( src[i] == '&' )
@@ -117,11 +118,11 @@ external_codefmt(char *src, int len, cha
     }
 
     /* 80 characters for the format wrappers */
-    if ( (res = malloc(len+extra+80+strlen(lang))) ==0 )
+    if ( (res = malloc(len+extra+80+strlen(ec_lang))) ==0 )
 	/* out of memory?  drat! */
 	return 0;
 
-    sprintf(res, "<pre><code class=\"%s\">\n", lang);
+    sprintf(res, "<pre><code class=\"%s\">\n", ec_lang);
     x = strlen(res);
     for ( i=0; i < len; i++ ) {
 	switch (src[i]) {