diff --git a/library/pkcs12.c b/library/pkcs12.c
index 3699dd5..80eb9db 100644
--- a/library/pkcs12.c
+++ b/library/pkcs12.c
@@ -179,6 +179,9 @@
     mbedtls_cipher_context_t cipher_ctx;
     size_t olen = 0;
 
+    if( pwd == NULL && pwdlen != 0 )
+        return( MBEDTLS_ERR_PKCS12_BAD_INPUT_DATA );
+
     cipher_info = mbedtls_cipher_info_from_type( cipher_type );
     if( cipher_info == NULL )
         return( MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE );
@@ -231,13 +234,18 @@
     unsigned char *p = data;
     size_t use_len;
 
-    while( data_len > 0 )
+    if( filler != NULL && fill_len != 0 )
     {
-        use_len = ( data_len > fill_len ) ? fill_len : data_len;
-        memcpy( p, filler, use_len );
-        p += use_len;
-        data_len -= use_len;
+        while( data_len > 0 )
+        {
+            use_len = ( data_len > fill_len ) ? fill_len : data_len;
+            memcpy( p, filler, use_len );
+            p += use_len;
+            data_len -= use_len;
+        }
     }
+    else
+        memset( data, 0, data_len );
 }
 
 int mbedtls_pkcs12_derivation( unsigned char *data, size_t datalen,
@@ -263,6 +271,9 @@
     if( datalen > 128 || pwdlen > 64 || saltlen > 64 )
         return( MBEDTLS_ERR_PKCS12_BAD_INPUT_DATA );
 
+    if( pwd == NULL && pwdlen != 0 )
+        return( MBEDTLS_ERR_PKCS12_BAD_INPUT_DATA );
+
     md_info = mbedtls_md_info_from_type( md_type );
     if( md_info == NULL )
         return( MBEDTLS_ERR_PKCS12_FEATURE_UNAVAILABLE );