diff --git a/apache2/msc_util.c b/apache2/msc_util.c
index dc1e8cb2..c452e18e 100644
--- a/apache2/msc_util.c
+++ b/apache2/msc_util.c
@@ -121,9 +121,9 @@ int parse_boolean(const char *input) {
  * \retval 0 On failure
  * \retval string length On Success
  */
-int decode_base64_ext(char *plain_text, const char *input, int input_len)
+int decode_base64_ext(char *plain_text, const unsigned char *input, int input_len)
 {
-    const char *encoded = input;
+    const unsigned char *encoded = input;
     int i = 0, j = 0, k = 0;
     int ch = 0;
 
diff --git a/apache2/msc_util.h b/apache2/msc_util.h
index cde36e94..9ebc80e3 100644
--- a/apache2/msc_util.h
+++ b/apache2/msc_util.h
@@ -81,7 +81,7 @@ char DSOLOCAL *log_escape_raw(apr_pool_t *mp, const unsigned char *text, unsigne
 
 char DSOLOCAL *log_escape_nul(apr_pool_t *mp, const unsigned char *text, unsigned long int text_length);
 
-int DSOLOCAL decode_base64_ext(char *plain_text, const char *input, int input_len);
+int DSOLOCAL decode_base64_ext(char *plain_text, const unsigned char *input, int input_len);
 
 int DSOLOCAL convert_to_int(const char c);
 
diff --git a/apache2/re_tfns.c b/apache2/re_tfns.c
index ebfff723..08a4389d 100644
--- a/apache2/re_tfns.c
+++ b/apache2/re_tfns.c
@@ -736,7 +736,7 @@ static int msre_fn_base64DecodeExt_execute(apr_pool_t *mptmp, unsigned char *inp
 {
     *rval_len = input_len;
     *rval = apr_palloc(mptmp, *rval_len);
-    *rval_len = decode_base64_ext(*rval, (const char *)input, input_len);
+    *rval_len = decode_base64_ext(*rval, (const unsigned char *)input, input_len);
 
     return *rval_len ? 1 : 0;
 }