diff --git a/src/http/zcl_abapgit_http_digest.clas.abap b/src/http/zcl_abapgit_http_digest.clas.abap
index 8b72a7767..716b00163 100644
--- a/src/http/zcl_abapgit_http_digest.clas.abap
+++ b/src/http/zcl_abapgit_http_digest.clas.abap
@@ -17,6 +17,7 @@ CLASS zcl_abapgit_http_digest DEFINITION
       RAISING
         zcx_abapgit_exception.
 
+  PROTECTED SECTION.
   PRIVATE SECTION.
     DATA: mv_ha1      TYPE string,
           mv_username TYPE string,
@@ -83,26 +84,23 @@ CLASS ZCL_ABAPGIT_HTTP_DIGEST IMPLEMENTATION.
 
   METHOD md5.
 
-    DATA: lv_xstr TYPE xstring,
-          lv_hash TYPE xstring.
-
+    DATA lv_xstr TYPE xstring.
+    DATA lv_hash TYPE xstring.
+    DATA lv_empty TYPE xstring.
 
     lv_xstr = zcl_abapgit_convert=>string_to_xstring_utf8( iv_data ).
 
-    CALL FUNCTION 'CALCULATE_HASH_FOR_RAW'
-      EXPORTING
-        alg            = 'MD5'
-        data           = lv_xstr
-      IMPORTING
-        hashxstring    = lv_hash
-      EXCEPTIONS
-        unknown_alg    = 1
-        param_error    = 2
-        internal_error = 3
-        OTHERS         = 4.
-    IF sy-subrc <> 0.
-      zcx_abapgit_exception=>raise( 'error from CALCULATE_HASH_FOR_RAW' ).
-    ENDIF.
+    TRY.
+        cl_abap_hmac=>calculate_hmac_for_raw(
+          EXPORTING
+            if_algorithm   = 'MD5'
+            if_key         = lv_empty
+            if_data        = lv_xstr
+          IMPORTING
+            ef_hmacxstring = lv_hash ).
+      CATCH cx_abap_message_digest.
+        zcx_abapgit_exception=>raise( 'error calculating md5' ).
+    ENDTRY.
 
     rv_hash = lv_hash.
     TRANSLATE rv_hash TO LOWER CASE.