diff --git a/Python/fileutils.c b/Python/fileutils.c
index d610639..3cf8b7a 100644
--- a/Python/fileutils.c
+++ b/Python/fileutils.c
@@ -913,6 +913,7 @@
 }
 
 
+/* This function MUST be kept async-signal-safe on POSIX when raise=0. */
 static int
 get_inheritable(int fd, int raise)
 {
@@ -958,6 +959,8 @@
     return get_inheritable(fd, 1);
 }
 
+
+/* This function MUST be kept async-signal-safe on POSIX when raise=0. */
 static int
 set_inheritable(int fd, int inheritable, int raise, int *atomic_flag_works)
 {
@@ -1014,8 +1017,10 @@
 #else
 
 #if defined(HAVE_SYS_IOCTL_H) && defined(FIOCLEX) && defined(FIONCLEX)
-    if (ioctl_works != 0) {
+    if (ioctl_works != 0 && raise != 0) {
         /* fast-path: ioctl() only requires one syscall */
+        /* caveat: raise=0 is an indicator that we must be async-signal-safe
+         * thus avoid using ioctl() so we skip the fast-path. */
         if (inheritable)
             request = FIONCLEX;
         else
@@ -1086,8 +1091,7 @@
 }
 
 /* Set the inheritable flag of the specified file descriptor.
-   On success: return 0, on error: raise an exception if raise is nonzero
-   and return -1.
+   On success: return 0, on error: raise an exception and return -1.
 
    If atomic_flag_works is not NULL:
 
@@ -1108,6 +1112,15 @@
     return set_inheritable(fd, inheritable, 1, atomic_flag_works);
 }
 
+/* Same as _Py_set_inheritable() but on error, set errno and
+   don't raise an exception.
+   This function is async-signal-safe. */
+int
+_Py_set_inheritable_async_safe(int fd, int inheritable, int *atomic_flag_works)
+{
+    return set_inheritable(fd, inheritable, 0, atomic_flag_works);
+}
+
 static int
 _Py_open_impl(const char *pathname, int flags, int gil_held)
 {