diff --git a/net/tap-bsd.c b/net/tap-bsd.c
index 7e65bd391f..005ce05c6e 100644
--- a/net/tap-bsd.c
+++ b/net/tap-bsd.c
@@ -98,7 +98,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
             return -1;
         }
     }
-    fcntl(fd, F_SETFL, O_NONBLOCK);
+    g_unix_set_fd_nonblocking(fd, true, NULL);
     return fd;
 }
 
@@ -189,7 +189,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
         goto error;
     }
 
-    fcntl(fd, F_SETFL, O_NONBLOCK);
+    g_unix_set_fd_nonblocking(fd, true, NULL);
     return fd;
 
 error:
diff --git a/net/tap-linux.c b/net/tap-linux.c
index 3e24d232e7..304ff45071 100644
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -113,7 +113,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
         return -1;
     }
     pstrcpy(ifname, ifname_size, ifr.ifr_name);
-    fcntl(fd, F_SETFL, O_NONBLOCK);
+    g_unix_set_fd_nonblocking(fd, true, NULL);
     return fd;
 }
 
diff --git a/net/tap-solaris.c b/net/tap-solaris.c
index 79919785c9..a44f8805c2 100644
--- a/net/tap-solaris.c
+++ b/net/tap-solaris.c
@@ -198,7 +198,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr,
             return -1;
         }
     }
-    fcntl(fd, F_SETFL, O_NONBLOCK);
+    g_unix_set_fd_nonblocking(fd, true, NULL);
     return fd;
 }
 
diff --git a/tests/qtest/fuzz/virtio_net_fuzz.c b/tests/qtest/fuzz/virtio_net_fuzz.c
index 3df78d9c1c..c2c15f07f0 100644
--- a/tests/qtest/fuzz/virtio_net_fuzz.c
+++ b/tests/qtest/fuzz/virtio_net_fuzz.c
@@ -151,7 +151,7 @@ static void *virtio_net_test_setup_socket(GString *cmd_line, void *arg)
 {
     int ret = socketpair(PF_UNIX, SOCK_STREAM, 0, sockfds);
     g_assert_cmpint(ret, !=, -1);
-    fcntl(sockfds[0], F_SETFL, O_NONBLOCK);
+    g_unix_set_fd_nonblocking(sockfds[0], true, NULL);
     sockfds_initialized = true;
     g_string_append_printf(cmd_line, " -netdev socket,fd=%d,id=hs0 ",
                            sockfds[1]);
diff --git a/tests/unit/test-iov.c b/tests/unit/test-iov.c
index 0d2ba9ba87..93bda00f0e 100644
--- a/tests/unit/test-iov.c
+++ b/tests/unit/test-iov.c
@@ -186,7 +186,7 @@ static void test_io(void)
 
        close(sv[0]);
        FD_SET(sv[1], &fds);
-       fcntl(sv[1], F_SETFL, O_RDWR|O_NONBLOCK);
+       g_unix_set_fd_nonblocking(sv[1], true, NULL);
        r = g_test_rand_int_range(sz / 2, sz);
        setsockopt(sv[1], SOL_SOCKET, SO_SNDBUF, &r, sizeof(r));
 
@@ -220,7 +220,7 @@ static void test_io(void)
 
        close(sv[1]);
        FD_SET(sv[0], &fds);
-       fcntl(sv[0], F_SETFL, O_RDWR|O_NONBLOCK);
+       g_unix_set_fd_nonblocking(sv[0], true, NULL);
        r = g_test_rand_int_range(sz / 2, sz);
        setsockopt(sv[0], SOL_SOCKET, SO_RCVBUF, &r, sizeof(r));
        usleep(500000);
diff --git a/util/oslib-posix.c b/util/oslib-posix.c
index 2a6f6248ad..72f25e599d 100644
--- a/util/oslib-posix.c
+++ b/util/oslib-posix.c
@@ -226,24 +226,12 @@ void qemu_anon_ram_free(void *ptr, size_t size)
 
 void qemu_set_block(int fd)
 {
-    int f;
-    f = fcntl(fd, F_GETFL);
-    assert(f != -1);
-    f = fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
-    assert(f != -1);
+    g_unix_set_fd_nonblocking(fd, false, NULL);
 }
 
 int qemu_try_set_nonblock(int fd)
 {
-    int f;
-    f = fcntl(fd, F_GETFL);
-    if (f == -1) {
-        return -errno;
-    }
-    if (fcntl(fd, F_SETFL, f | O_NONBLOCK) == -1) {
-        return -errno;
-    }
-    return 0;
+    return g_unix_set_fd_nonblocking(fd, true, NULL) ? 0 : -errno;
 }
 
 void qemu_set_nonblock(int fd)