diff --git a/tests/src/test_helpers/ssl_helpers.c b/tests/src/test_helpers/ssl_helpers.c
index 3a1e301..dd24fea 100644
--- a/tests/src/test_helpers/ssl_helpers.c
+++ b/tests/src/test_helpers/ssl_helpers.c
@@ -950,7 +950,7 @@
 /*
  * Write application data. Increase write counter if necessary.
  */
-int mbedtls_ssl_write_fragment(mbedtls_ssl_context *ssl,
+static int mbedtls_ssl_write_fragment(mbedtls_ssl_context *ssl,
                                unsigned char *buf, int buf_len,
                                int *written,
                                const int expected_fragments)
@@ -997,7 +997,7 @@
  * Read application data and increase read counter and fragments counter
  * if necessary.
  */
-int mbedtls_ssl_read_fragment(mbedtls_ssl_context *ssl,
+static int mbedtls_ssl_read_fragment(mbedtls_ssl_context *ssl,
                               unsigned char *buf, int buf_len,
                               int *read, int *fragments,
                               const int expected_fragments)
diff --git a/tests/suites/test_suite_debug.function b/tests/suites/test_suite_debug.function
index 5cd02b9..a71db14 100644
--- a/tests/suites/test_suite_debug.function
+++ b/tests/suites/test_suite_debug.function
@@ -9,7 +9,7 @@
     char *ptr;
 };
 
-void string_debug(void *data, int level, const char *file, int line, const char *str)
+static void string_debug(void *data, int level, const char *file, int line, const char *str)
 {
     struct buffer_data *buffer = (struct buffer_data *) data;
     char *p = buffer->ptr;
diff --git a/tests/suites/test_suite_pkcs7.function b/tests/suites/test_suite_pkcs7.function
index 4c8bf23..e5dc4bd 100644
--- a/tests/suites/test_suite_pkcs7.function
+++ b/tests/suites/test_suite_pkcs7.function
@@ -17,7 +17,7 @@
  * END_DEPENDENCIES
  */
 /* BEGIN_SUITE_HELPERS */
-int pkcs7_parse_buffer(unsigned char *pkcs7_buf, int buflen)
+static int pkcs7_parse_buffer(unsigned char *pkcs7_buf, int buflen)
 {
     int res;
     mbedtls_pkcs7 pkcs7;
diff --git a/tests/suites/test_suite_x509parse.function b/tests/suites/test_suite_x509parse.function
index ba71c8f..e72a6e3 100644
--- a/tests/suites/test_suite_x509parse.function
+++ b/tests/suites/test_suite_x509parse.function
@@ -60,7 +60,7 @@
     1024,
 };
 
-int verify_none(void *data, mbedtls_x509_crt *crt, int certificate_depth, uint32_t *flags)
+static int verify_none(void *data, mbedtls_x509_crt *crt, int certificate_depth, uint32_t *flags)
 {
     ((void) data);
     ((void) crt);
@@ -70,7 +70,7 @@
     return 0;
 }
 
-int verify_all(void *data, mbedtls_x509_crt *crt, int certificate_depth, uint32_t *flags)
+static int verify_all(void *data, mbedtls_x509_crt *crt, int certificate_depth, uint32_t *flags)
 {
     ((void) data);
     ((void) crt);
@@ -81,7 +81,7 @@
 }
 
 #if defined(MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK)
-int ca_callback_fail(void *data, mbedtls_x509_crt const *child, mbedtls_x509_crt **candidates)
+static int ca_callback_fail(void *data, mbedtls_x509_crt const *child, mbedtls_x509_crt **candidates)
 {
     ((void) data);
     ((void) child);
@@ -90,7 +90,7 @@
     return -1;
 }
 #if defined(MBEDTLS_X509_CRT_PARSE_C)
-int ca_callback(void *data, mbedtls_x509_crt const *child,
+static int ca_callback(void *data, mbedtls_x509_crt const *child,
                 mbedtls_x509_crt **candidates)
 {
     int ret = 0;
@@ -141,7 +141,7 @@
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 #endif /* MBEDTLS_X509_TRUSTED_CERTIFICATE_CALLBACK */
 
-int verify_fatal(void *data, mbedtls_x509_crt *crt, int certificate_depth, uint32_t *flags)
+static int verify_fatal(void *data, mbedtls_x509_crt *crt, int certificate_depth, uint32_t *flags)
 {
     int *levels = (int *) data;
 
@@ -158,7 +158,7 @@
 }
 
 /* strsep() not available on Windows */
-char *mystrsep(char **stringp, const char *delim)
+static char *mystrsep(char **stringp, const char *delim)
 {
     const char *p;
     char *ret = *stringp;
@@ -192,13 +192,13 @@
     char *p;
 } verify_print_context;
 
-void verify_print_init(verify_print_context *ctx)
+static void verify_print_init(verify_print_context *ctx)
 {
     memset(ctx, 0, sizeof(verify_print_context));
     ctx->p = ctx->buf;
 }
 
-int verify_print(void *data, mbedtls_x509_crt *crt, int certificate_depth, uint32_t *flags)
+static int verify_print(void *data, mbedtls_x509_crt *crt, int certificate_depth, uint32_t *flags)
 {
     int ret;
     verify_print_context *ctx = (verify_print_context *) data;
@@ -226,7 +226,7 @@
     return 0;
 }
 
-int verify_parse_san(mbedtls_x509_subject_alternative_name *san,
+static int verify_parse_san(mbedtls_x509_subject_alternative_name *san,
                      char **buf, size_t *size)
 {
     int ret;
@@ -317,7 +317,7 @@
     return 0;
 }
 
-int parse_crt_ext_cb(void *p_ctx, mbedtls_x509_crt const *crt, mbedtls_x509_buf const *oid,
+static int parse_crt_ext_cb(void *p_ctx, mbedtls_x509_crt const *crt, mbedtls_x509_buf const *oid,
                      int critical, const unsigned char *cp, const unsigned char *end)
 {
     (void) crt;
@@ -417,7 +417,7 @@
 #endif /* MBEDTLS_X509_CRT_PARSE_C */
 
 #if defined(MBEDTLS_X509_CSR_PARSE_C)
-int parse_csr_ext_accept_cb(void *p_ctx, mbedtls_x509_csr const *csr, mbedtls_x509_buf const *oid,
+static int parse_csr_ext_accept_cb(void *p_ctx, mbedtls_x509_csr const *csr, mbedtls_x509_buf const *oid,
                             int critical, const unsigned char *cp, const unsigned char *end)
 {
     (void) p_ctx;
@@ -430,7 +430,7 @@
     return 0;
 }
 
-int parse_csr_ext_reject_cb(void *p_ctx, mbedtls_x509_csr const *csr, mbedtls_x509_buf const *oid,
+static int parse_csr_ext_reject_cb(void *p_ctx, mbedtls_x509_csr const *csr, mbedtls_x509_buf const *oid,
                             int critical, const unsigned char *cp, const unsigned char *end)
 {
     (void) p_ctx;
diff --git a/tests/suites/test_suite_x509write.function b/tests/suites/test_suite_x509write.function
index 1db7e1c..820b48d 100644
--- a/tests/suites/test_suite_x509write.function
+++ b/tests/suites/test_suite_x509write.function
@@ -11,14 +11,14 @@
 #include "mbedtls/psa_util.h"
 
 #if defined(MBEDTLS_RSA_C)
-int mbedtls_rsa_decrypt_func(void *ctx, size_t *olen,
+static int mbedtls_rsa_decrypt_func(void *ctx, size_t *olen,
                              const unsigned char *input, unsigned char *output,
                              size_t output_max_len)
 {
     return mbedtls_rsa_pkcs1_decrypt((mbedtls_rsa_context *) ctx, NULL, NULL,
                                      olen, input, output, output_max_len);
 }
-int mbedtls_rsa_sign_func(void *ctx,
+static int mbedtls_rsa_sign_func(void *ctx,
                           int (*f_rng)(void *, unsigned char *, size_t), void *p_rng,
                           mbedtls_md_type_t md_alg, unsigned int hashlen,
                           const unsigned char *hash, unsigned char *sig)
@@ -26,7 +26,7 @@
     return mbedtls_rsa_pkcs1_sign((mbedtls_rsa_context *) ctx, f_rng, p_rng,
                                   md_alg, hashlen, hash, sig);
 }
-size_t mbedtls_rsa_key_len_func(void *ctx)
+static size_t mbedtls_rsa_key_len_func(void *ctx)
 {
     return ((const mbedtls_rsa_context *) ctx)->len;
 }