diff --git a/requirements.txt b/requirements.txt
index a495e41..15e409c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,5 +2,5 @@ pyparsing>=2.1.0,<3
 olefile>=0.46
 easygui
 colorclass
-msoffcrypto-tool; platform_python_implementation!="PyPy" or platform_system!="Windows"
+msoffcrypto-tool; platform_python_implementation!="PyPy" or (python_version>="3" and platform_system!="Windows" and platform_system!="Darwin")
 pcodedmp>=1.2.5
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 7c53562..611d205 100644
--- a/setup.py
+++ b/setup.py
@@ -323,7 +323,7 @@ def main():
             'colorclass',
             # msoffcrypto-tool is not installable on PyPy+Windows (see issue #473),
             # so we only require it if the platform is not Windows or not PyPy:
-            'msoffcrypto-tool; platform_python_implementation!="PyPy" or platform_system!="Windows"',
+            'msoffcrypto-tool; platform_python_implementation!="PyPy" or (python_version>="3" and platform_system!="Windows" and platform_system!="Darwin")',
             'pcodedmp>=1.2.5',
         ],
     )