diff --git a/OpenSSL/crypto.py b/OpenSSL/crypto.py
index 65e28d7..4d0867e 100644
--- a/OpenSSL/crypto.py
+++ b/OpenSSL/crypto.py
@@ -2215,7 +2215,7 @@
 
 
 
-def load_pkcs12(buffer, passphrase):
+def load_pkcs12(buffer, passphrase=None):
     """
     Load a PKCS12 object from a buffer
 
@@ -2228,6 +2228,13 @@
 
     bio = _new_mem_buf(buffer)
 
+    # Use null passphrase if passphrase is None or empty string. With PKCS#12
+    # password based encryption no password and a zero length password are two
+    # different things, but OpenSSL implementation will try both to figure out
+    # which one works.
+    if not passphrase:
+        passphrase = _ffi.NULL
+
     p12 = _lib.d2i_PKCS12_bio(bio, _ffi.NULL)
     if p12 == _ffi.NULL:
         _raise_current_error()