diff --git a/ChangeLog.d/fix-pkcs12-null-password.txt b/ChangeLog.d/fix-pkcs12-null-password.txt
new file mode 100644
index 0000000..699575f
--- /dev/null
+++ b/ChangeLog.d/fix-pkcs12-null-password.txt
@@ -0,0 +1,2 @@
+Bugfix
+   * Fix issues in pkcs12 when a NULL and/or zero length password was supplied.
diff --git a/include/mbedtls/pkcs12.h b/include/mbedtls/pkcs12.h
index ba9180b..fbf2378 100644
--- a/include/mbedtls/pkcs12.h
+++ b/include/mbedtls/pkcs12.h
@@ -79,11 +79,13 @@
  * \brief            PKCS12 Password Based function (encryption / decryption)
  *                   for cipher-based and mbedtls_md-based PBE's
  *
- * \param pbe_params an ASN1 buffer containing the pkcs-12PbeParams structure
- * \param mode       either MBEDTLS_PKCS12_PBE_ENCRYPT or MBEDTLS_PKCS12_PBE_DECRYPT
+ * \param pbe_params an ASN1 buffer containing the pkcs-12 PbeParams structure
+ * \param mode       either MBEDTLS_PKCS12_PBE_ENCRYPT or
+ *                   MBEDTLS_PKCS12_PBE_DECRYPT
  * \param cipher_type the cipher used
- * \param md_type     the mbedtls_md used
- * \param pwd        the password used (may be NULL if no password is used)
+ * \param md_type    the mbedtls_md used
+ * \param pwd        Latin1-encoded password used (may be NULL if no password is
+ *                   used, but not if pwdlen is non-zero)
  * \param pwdlen     length of the password (may be 0)
  * \param input      the input data
  * \param len        data length
@@ -108,14 +110,16 @@
  *                   integrity key.
  *
  * \param data       buffer to store the derived data in
- * \param datalen    length to fill
- * \param pwd        password to use (may be NULL if no password is used)
+ * \param datalen    length of buffer to fill
+ * \param pwd        Null terminated BMPString password to use (may be NULL if
+ *                   no password is used, but not if pwdlen is non-zero)
  * \param pwdlen     length of the password (may be 0)
  * \param salt       salt buffer to use
  * \param saltlen    length of the salt
- * \param mbedtls_md         mbedtls_md type to use during the derivation
- * \param id         id that describes the purpose (can be MBEDTLS_PKCS12_DERIVE_KEY,
- *                   MBEDTLS_PKCS12_DERIVE_IV or MBEDTLS_PKCS12_DERIVE_MAC_KEY)
+ * \param mbedtls_md mbedtls_md type to use during the derivation
+ * \param id         id that describes the purpose (can be
+ *                   MBEDTLS_PKCS12_DERIVE_KEY, MBEDTLS_PKCS12_DERIVE_IV or
+ *                   MBEDTLS_PKCS12_DERIVE_MAC_KEY)
  * \param iterations number of iterations
  *
  * \return          0 if successful, or a MD, BIGNUM type error.
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 );