diff --git a/library/ecp.c b/library/ecp.c
index 049a1e015..29f5bc77f 100644
--- a/library/ecp.c
+++ b/library/ecp.c
@@ -3639,7 +3639,7 @@ cleanup:
 #if defined(MBEDTLS_TEST_HOOKS)
 
 MBEDTLS_STATIC_TESTABLE
-mbedtls_ecp_variant mbedtls_ecp_get_variant()
+mbedtls_ecp_variant mbedtls_ecp_get_variant(void)
 {
     return MBEDTLS_ECP_VARIANT_WITH_MPI_STRUCT;
 }
diff --git a/programs/fuzz/common.c b/programs/fuzz/common.c
index 75021bb2f..98aa4037b 100644
--- a/programs/fuzz/common.c
+++ b/programs/fuzz/common.c
@@ -13,7 +13,7 @@ mbedtls_time_t dummy_constant_time(mbedtls_time_t *time)
 }
 #endif
 
-void dummy_init()
+void dummy_init(void)
 {
 #if defined(MBEDTLS_PLATFORM_TIME_ALT)
     mbedtls_platform_set_time(dummy_constant_time);
diff --git a/programs/fuzz/common.h b/programs/fuzz/common.h
index bc817bd76..094383c7a 100644
--- a/programs/fuzz/common.h
+++ b/programs/fuzz/common.h
@@ -15,7 +15,7 @@ typedef struct fuzzBufferOffset {
 #if defined(MBEDTLS_HAVE_TIME)
 mbedtls_time_t dummy_constant_time(mbedtls_time_t *time);
 #endif
-void dummy_init();
+void dummy_init(void);
 
 int dummy_send(void *ctx, const unsigned char *buf, size_t len);
 int fuzz_recv(void *ctx, unsigned char *buf, size_t len);
diff --git a/programs/ssl/ssl_context_info.c b/programs/ssl/ssl_context_info.c
index a5f065032..855b0911f 100644
--- a/programs/ssl/ssl_context_info.c
+++ b/programs/ssl/ssl_context_info.c
@@ -125,12 +125,12 @@ const char buf_ln_err[] = "Buffer does not have enough data to complete the pars
 /*
  * Basic printing functions
  */
-void print_version()
+void print_version(void)
 {
     printf("%s v%d.%d\n", PROG_NAME, VER_MAJOR, VER_MINOR);
 }
 
-void print_usage()
+void print_usage(void)
 {
     print_version();
     printf("\nThis program is used to deserialize an Mbed TLS SSL session from the base64 code provided\n"
@@ -179,7 +179,7 @@ void printf_err(const char *str, ...)
 /*
  * Exit from the program in case of error
  */
-void error_exit()
+void error_exit(void)
 {
     if (NULL != b64_file) {
         fclose(b64_file);
diff --git a/programs/test/udp_proxy.c b/programs/test/udp_proxy.c
index ac527f257..685e336e6 100644
--- a/programs/test/udp_proxy.c
+++ b/programs/test/udp_proxy.c
@@ -644,7 +644,7 @@ void delay_packet(packet *delay)
     memcpy(&prev[prev_len++], delay, sizeof(packet));
 }
 
-int send_delayed()
+int send_delayed(void)
 {
     uint8_t offset;
     int ret;
diff --git a/tests/scripts/generate_test_code.py b/tests/scripts/generate_test_code.py
index ff7f9b997..c42f9a84b 100755
--- a/tests/scripts/generate_test_code.py
+++ b/tests/scripts/generate_test_code.py
@@ -667,6 +667,11 @@ def parse_function_code(funcs_f, dependencies, suite_dependencies):
     code = code.replace(name, 'test_' + name, 1)
     name = 'test_' + name
 
+    # If a test function has no arguments then add 'void' argument to
+    # avoid "-Wstrict-prototypes" warnings from clang-16
+    if len(args) == 0:
+        code = code.replace('()', '(void)', 1)
+
     for line in funcs_f:
         if re.search(END_CASE_REGEX, line):
             break
diff --git a/tests/scripts/test_generate_test_code.py b/tests/scripts/test_generate_test_code.py
index fe748aeb4..b32d18423 100755
--- a/tests/scripts/test_generate_test_code.py
+++ b/tests/scripts/test_generate_test_code.py
@@ -647,7 +647,7 @@ void func()
         self.assertEqual(arg, [])
         expected = '''#line 1 "test_suite_ut.function"
 
-void test_func()
+void test_func(void)
 {
     ba ba black sheep
     have you any wool
@@ -690,7 +690,7 @@ exit:
 
         expected = '''#line 1 "test_suite_ut.function"
 
-void test_func()
+void test_func(void)
 {
     ba ba black sheep
     have you any wool
@@ -750,7 +750,7 @@ exit:
 void
 
 
-test_func()
+test_func(void)
 {
     ba ba black sheep
     have you any wool
@@ -803,7 +803,7 @@ exit:
 
 
 
-void test_func()
+void test_func(void)
 {
     ba ba black sheep
     have you any wool
@@ -1139,7 +1139,7 @@ void func2()
 #if defined(MBEDTLS_ENTROPY_NV_SEED)
 #if defined(MBEDTLS_FS_IO)
 #line 13 "test_suite_ut.function"
-void test_func1()
+void test_func1(void)
 {
 exit:
     ;
@@ -1156,7 +1156,7 @@ void test_func1_wrapper( void ** params )
 #if defined(MBEDTLS_ENTROPY_NV_SEED)
 #if defined(MBEDTLS_FS_IO)
 #line 19 "test_suite_ut.function"
-void test_func2()
+void test_func2(void)
 {
 exit:
     ;