diff --git a/scripts/mbedtls_dev/test_case.py b/scripts/mbedtls_dev/test_case.py
index 6a46e4209..d0afa592f 100644
--- a/scripts/mbedtls_dev/test_case.py
+++ b/scripts/mbedtls_dev/test_case.py
@@ -92,9 +92,11 @@ def write_data_file(filename: str,
     """
     if caller is None:
         caller = os.path.basename(sys.argv[0])
-    with open(filename, 'w') as out:
+    tempfile = filename + '.new'
+    with open(tempfile, 'w') as out:
         out.write('# Automatically generated by {}. Do not edit!\n'
                   .format(caller))
         for tc in test_cases:
             tc.write(out)
         out.write('\n# End of automatically generated file.\n')
+    os.replace(tempfile, filename)
diff --git a/tests/include/test/helpers.h b/tests/include/test/helpers.h
index 0d97e80e5..757a43be4 100644
--- a/tests/include/test/helpers.h
+++ b/tests/include/test/helpers.h
@@ -58,6 +58,13 @@
 #include "mbedtls/bignum.h"
 #endif
 
+/** The type of test case arguments that contain binary data. */
+typedef struct data_tag
+{
+    uint8_t *   x;
+    uint32_t    len;
+} data_t;
+
 typedef enum
 {
     MBEDTLS_TEST_RESULT_SUCCESS = 0,
@@ -379,7 +386,6 @@ void mbedtls_test_err_add_check( int high, int low,
  *
  * \return \c 0 on success, an \c MBEDTLS_ERR_MPI_xxx error code otherwise.
  */
-/* Since the library has exactly the desired behavior, this is trivial. */
 int mbedtls_test_read_mpi( mbedtls_mpi *X, const char *s );
 #endif /* MBEDTLS_BIGNUM_C */
 
diff --git a/tests/src/helpers.c b/tests/src/helpers.c
index c310d48e7..bfd21893d 100644
--- a/tests/src/helpers.c
+++ b/tests/src/helpers.c
@@ -15,6 +15,7 @@
  *  limitations under the License.
  */
 
+#include <test/constant_flow.h>
 #include <test/helpers.h>
 #include <test/macros.h>
 #include <string.h>
@@ -120,8 +121,12 @@ void mbedtls_test_info_reset( void )
 int mbedtls_test_equal( const char *test, int line_no, const char* filename,
                         unsigned long long value1, unsigned long long value2 )
 {
+    TEST_CF_PUBLIC( &value1, sizeof( value1 ) );
+    TEST_CF_PUBLIC( &value2, sizeof( value2 ) );
+
     if( value1 == value2 )
         return( 1 );
+
     if( mbedtls_test_info.result == MBEDTLS_TEST_RESULT_FAILED )
     {
         /* We've already recorded the test as having failed. Don't
@@ -143,8 +148,12 @@ int mbedtls_test_equal( const char *test, int line_no, const char* filename,
 int mbedtls_test_le_u( const char *test, int line_no, const char* filename,
                        unsigned long long value1, unsigned long long value2 )
 {
+    TEST_CF_PUBLIC( &value1, sizeof( value1 ) );
+    TEST_CF_PUBLIC( &value2, sizeof( value2 ) );
+
     if( value1 <= value2 )
         return( 1 );
+
     if( mbedtls_test_info.result == MBEDTLS_TEST_RESULT_FAILED )
     {
         /* We've already recorded the test as having failed. Don't
@@ -166,8 +175,12 @@ int mbedtls_test_le_u( const char *test, int line_no, const char* filename,
 int mbedtls_test_le_s( const char *test, int line_no, const char* filename,
                        long long value1, long long value2 )
 {
+    TEST_CF_PUBLIC( &value1, sizeof( value1 ) );
+    TEST_CF_PUBLIC( &value2, sizeof( value2 ) );
+
     if( value1 <= value2 )
         return( 1 );
+
     if( mbedtls_test_info.result == MBEDTLS_TEST_RESULT_FAILED )
     {
         /* We've already recorded the test as having failed. Don't
diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 91ad925fb..a7531e700 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -51,13 +51,6 @@ typedef UINT32 uint32_t;
 #include <strings.h>
 #endif
 
-/* Type for Hex parameters */
-typedef struct data_tag
-{
-    uint8_t *   x;
-    uint32_t    len;
-} data_t;
-
 /*----------------------------------------------------------------------------*/
 /* Status and error constants */