diff --git a/Python/clinic/sysmodule.c.h b/Python/clinic/sysmodule.c.h
index 1f09e02..2f3bd14 100644
--- a/Python/clinic/sysmodule.c.h
+++ b/Python/clinic/sysmodule.c.h
@@ -306,9 +306,15 @@
     PyObject *return_value = NULL;
     double interval;
 
-    interval = PyFloat_AsDouble(arg);
-    if (PyErr_Occurred()) {
-        goto exit;
+    if (PyFloat_CheckExact(arg)) {
+        interval = PyFloat_AS_DOUBLE(arg);
+    }
+    else
+    {
+        interval = PyFloat_AsDouble(arg);
+        if (interval == -1.0 && PyErr_Occurred()) {
+            goto exit;
+        }
     }
     return_value = sys_setswitchinterval_impl(module, interval);
 
@@ -989,4 +995,4 @@
 #ifndef SYS_GETANDROIDAPILEVEL_METHODDEF
     #define SYS_GETANDROIDAPILEVEL_METHODDEF
 #endif /* !defined(SYS_GETANDROIDAPILEVEL_METHODDEF) */
-/*[clinic end generated code: output=acef77d2bb8f6da9 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=b26faa0abdd700da input=a9049054013a1b77]*/