diff --git a/PCbuild/build_ssl.py b/PCbuild/build_ssl.py
index 526eba3..151aa54 100644
--- a/PCbuild/build_ssl.py
+++ b/PCbuild/build_ssl.py
@@ -207,9 +207,9 @@
 
         # Now run make.
         if arch == "amd64":
-            rc = os.system(r"ml64 -c -Foms\uptable.obj ms\uptable.asm")
+            rc = os.system("nasm -f win64 -DNEAR -Ox -g ms\\uptable.asm")
             if rc:
-                print("ml64 assembler has failed.")
+                print("nasm assembler has failed.")
                 sys.exit(rc)
 
         shutil.copy(r"crypto\buildinf_%s.h" % arch, r"crypto\buildinf.h")