diff --git a/morgan/__init__.py b/morgan/__init__.py
index 755fed9..021fbcb 100644
--- a/morgan/__init__.py
+++ b/morgan/__init__.py
@@ -64,11 +64,15 @@ def __init__(self, args: argparse.Namespace):
                     self._supported_pyversions.append(env["python_version"])
                 if "platform_tag" in env:
                     self._supported_platforms.append(re.compile(env["platform_tag"]))
-                self._supported_platforms.append(
-                    re.compile(
-                        r".*" + env["sys_platform"] + r".*" + env["platform_machine"]
+                else:
+                    self._supported_platforms.append(
+                        re.compile(
+                            r".*"
+                            + env["sys_platform"]
+                            + r".*"
+                            + env["platform_machine"]
+                        )
                     )
-                )
 
         self._processed_pkgs = Cache()