diff --git a/library/md4.c b/library/md4.c
index ccde1a1..f6b71d5 100644
--- a/library/md4.c
+++ b/library/md4.c
@@ -79,6 +79,19 @@
 }
 #endif
 
+void md4_init( md4_context *ctx )
+{
+    memset( ctx, 0, sizeof( md4_context ) );
+}
+
+void md4_free( md4_context *ctx )
+{
+    if( ctx == NULL )
+        return;
+
+    polarssl_zeroize( ctx, sizeof( md4_context ) );
+}
+
 /*
  * MD4 context setup
  */
@@ -285,11 +298,11 @@
 {
     md4_context ctx;
 
+    md4_init( &ctx );
     md4_starts( &ctx );
     md4_update( &ctx, input, ilen );
     md4_finish( &ctx, output );
-
-    polarssl_zeroize( &ctx, sizeof( md4_context ) );
+    md4_free( &ctx );
 }
 
 #if defined(POLARSSL_FS_IO)
@@ -306,14 +319,14 @@
     if( ( f = fopen( path, "rb" ) ) == NULL )
         return( POLARSSL_ERR_MD4_FILE_IO_ERROR );
 
+    md4_init( &ctx );
     md4_starts( &ctx );
 
     while( ( n = fread( buf, 1, sizeof( buf ), f ) ) > 0 )
         md4_update( &ctx, buf, n );
 
     md4_finish( &ctx, output );
-
-    polarssl_zeroize( &ctx, sizeof( md4_context ) );
+    md4_free( &ctx );
 
     if( ferror( f ) != 0 )
     {
@@ -400,11 +413,11 @@
 {
     md4_context ctx;
 
+    md4_init( &ctx );
     md4_hmac_starts( &ctx, key, keylen );
     md4_hmac_update( &ctx, input, ilen );
     md4_hmac_finish( &ctx, output );
-
-    polarssl_zeroize( &ctx, sizeof( md4_context ) );
+    md4_free( &ctx );
 }
 
 #if defined(POLARSSL_SELF_TEST)