diff --git a/components/esp-tls/esp_tls.c b/components/esp-tls/esp_tls.c
index af2be302d..ba9e75812 100644
--- a/components/esp-tls/esp_tls.c
+++ b/components/esp-tls/esp_tls.c
@@ -189,7 +189,11 @@ static esp_err_t esp_tcp_connect(const char *host, int hostlen, int port, int *s
         }
         if (cfg->non_block) {
             int flags = fcntl(fd, F_GETFL, 0);
-            fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+            ret = fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+            if (ret < 0) {
+                ESP_LOGE(TAG, "Failed to configure the socket as non-blocking (errno %d)", errno);
+                goto err_freesocket;
+            }
         }
     }
 
diff --git a/components/newlib/syscalls.c b/components/newlib/syscalls.c
index c3da628da..8b4b7aece 100644
--- a/components/newlib/syscalls.c
+++ b/components/newlib/syscalls.c
@@ -15,18 +15,31 @@
 #include <string.h>
 #include <stdbool.h>
 #include <stdlib.h>
+#include <stdarg.h>
 #include <sys/types.h>
 #include <unistd.h>
 #include <errno.h>
-#include <sys/reent.h>
+#include <reent.h>
+#include <sys/fcntl.h>
 
 
+int system(const char* str)
+{
+    errno = ENOSYS;
+    return -1;
+}
+
 int _system_r(struct _reent *r, const char *str)
 {
     __errno_r(r) = ENOSYS;
     return -1;
 }
 
+int raise(int sig)
+{
+    abort();
+}
+
 int _raise_r(struct _reent *r, int sig)
 {
     abort();
@@ -54,6 +67,17 @@ void _exit(int __status)
     abort();
 }
 
+/* Replaces newlib fcntl, which has been compiled without HAVE_FCNTL */
+int fcntl(int fd, int cmd, ...)
+{
+    va_list args;
+    va_start(args, cmd);
+    int arg = va_arg(args, int);
+    va_end(args);
+    struct _reent* r = __getreent();
+    return _fcntl_r(r, fd, cmd, arg);
+}
+
 /* No-op function, used to force linking this file,
    instead of the syscalls implementation from libgloss.
  */
diff --git a/components/newlib/test/test_newlib.c b/components/newlib/test/test_newlib.c
index 41f72329b..4cfec3e40 100644
--- a/components/newlib/test/test_newlib.c
+++ b/components/newlib/test/test_newlib.c
@@ -182,3 +182,8 @@ TEST_CASE("fmod and fmodf work as expected", "[newlib]")
     TEST_ASSERT_EQUAL(0.1, fmod(10.1, 2.0));
     TEST_ASSERT_EQUAL(0.1f, fmodf(10.1f, 2.0f));
 }
+
+TEST_CASE("newlib: can link 'system', 'raise'", "[newlib]")
+{
+    printf("system: %p, raise: %p\n", &system, &raise);
+}
diff --git a/components/vfs/test/test_vfs_uart.c b/components/vfs/test/test_vfs_uart.c
index 77815aed7..255e54f83 100644
--- a/components/vfs/test/test_vfs_uart.c
+++ b/components/vfs/test/test_vfs_uart.c
@@ -207,6 +207,17 @@ TEST_CASE("can write to UART while another task is reading", "[vfs]")
     vSemaphoreDelete(write_arg.done);
 }
 
+TEST_CASE("fcntl supported in UART VFS", "[vfs]")
+{
+    int flags = fcntl(STDIN_FILENO, F_GETFL, 0);
+    TEST_ASSERT_NOT_EQUAL(-1, flags);
+    int res = fcntl(STDIN_FILENO, F_SETFL, flags | O_NONBLOCK);
+    TEST_ASSERT_NOT_EQUAL(-1, res);
+    /* revert */
+    res = fcntl(STDIN_FILENO, F_SETFL, flags);
+    TEST_ASSERT_NOT_EQUAL(-1, res);
+}
+
 #ifdef CONFIG_VFS_SUPPORT_TERMIOS
 TEST_CASE("Can use termios for UART", "[vfs]")
 {
diff --git a/components/vfs/vfs.c b/components/vfs/vfs.c
index 65b558b6d..690896c57 100644
--- a/components/vfs/vfs.c
+++ b/components/vfs/vfs.c
@@ -725,16 +725,6 @@ int _fcntl_r(struct _reent *r, int fd, int cmd, int arg)
     return ret;
 }
 
-int __attribute__((weak)) fcntl(int fd, int cmd, ...)
-{
-    va_list args;
-    va_start(args, cmd);
-    int arg = va_arg(args, int);
-    va_end(args);
-    struct _reent* r = __getreent();
-    return _fcntl_r(r, fd, cmd, arg);
-}
-
 int ioctl(int fd, int cmd, ...)
 {
     const vfs_entry_t* vfs = get_vfs_for_fd(fd);