diff --git a/src/_pytest/config/__init__.py b/src/_pytest/config/__init__.py
index 25f156f8b..17500e798 100644
--- a/src/_pytest/config/__init__.py
+++ b/src/_pytest/config/__init__.py
@@ -697,6 +697,7 @@ class PytestPluginManager(PluginManager):
                     parg = opt[2:]
                 else:
                     continue
+                parg = parg.strip()
                 if exclude_only and not parg.startswith("no:"):
                     continue
                 self.consider_pluginarg(parg)