diff --git a/node.gyp b/node.gyp
index a14aa5813243ba..4cb368a8c6f334 100644
--- a/node.gyp
+++ b/node.gyp
@@ -372,9 +372,14 @@
                         '-Wl,--no-whole-archive',
                       ],
                     }],
+                    # openssl.def is based on zlib.def, zlib symbols
+                    # are always exported.
                     ['use_openssl_def==1', {
                       'sources': ['<(SHARED_INTERMEDIATE_DIR)/openssl.def'],
                     }],
+                    ['OS=="win" and use_openssl_def==0', {
+                      'sources': ['deps/zlib/win32/zlib.def'],
+                    }],
                   ],
                 }],
               ],
@@ -570,6 +575,8 @@
               '-X^DSO',
               '-X^_',
               '-X^private_',
+              # Base generated DEF on zlib.def
+              '-Bdeps/zlib/win32/zlib.def'
             ],
           },
           'conditions': [
diff --git a/tools/mkssldef.py b/tools/mkssldef.py
index 8cbdbabd976ba9..8354e5712ef099 100755
--- a/tools/mkssldef.py
+++ b/tools/mkssldef.py
@@ -7,6 +7,7 @@
 categories = []
 defines = []
 excludes = []
+bases = []
 
 if __name__ == '__main__':
   out = sys.stdout
@@ -18,6 +19,7 @@
     elif option.startswith('-C'): categories += option[2:].split(',')
     elif option.startswith('-D'): defines += option[2:].split(',')
     elif option.startswith('-X'): excludes += option[2:].split(',')
+    elif option.startswith('-B'): bases += option[2:].split(',')
 
   excludes = map(re.compile, excludes)
   exported = []
@@ -40,5 +42,12 @@ def test(expr):
       if not satisfy(meta[3], categories): continue
       exported.append(name)
 
+  for filename in bases:
+    for line in open(filename).readlines():
+      line = line.strip()
+      if line == 'EXPORTS': continue
+      if line[0] == ';': continue
+      exported.append(line)
+
   print('EXPORTS', file=out)
   for name in sorted(exported): print('    ', name, file=out)