diff --git a/src/_macosx.m b/src/_macosx.m
index 8038b72899df..299fed1785a8 100755
--- a/src/_macosx.m
+++ b/src/_macosx.m
@@ -461,6 +461,8 @@ int mpl_check_modifier(
         return NULL;
     }
 
+    Py_BEGIN_ALLOW_THREADS
+
     NSDate* date =
         (timeout > 0.0) ? [NSDate dateWithTimeIntervalSinceNow: timeout]
                         : [NSDate distantFuture];
@@ -473,6 +475,8 @@ int mpl_check_modifier(
        [NSApp sendEvent: event];
     }
 
+    Py_END_ALLOW_THREADS
+
     Py_RETURN_NONE;
 }