diff --git a/tests/io_num_hdf5.c b/tests/io_num_hdf5.c
index 4e04f1a..a16acc7 100644
--- a/tests/io_num_hdf5.c
+++ b/tests/io_num_hdf5.c
@@ -87,6 +87,7 @@ static int test_read_num (const char* file_name, const back_end_t backend) {
   // read numerical attribute from the file
   rc = trexio_read_nucleus_num(file, &num);
   assert (rc == TREXIO_SUCCESS);
+  assert (num == 12);
 
   // close current session
   rc = trexio_close(file);
diff --git a/tests/io_num_text.c b/tests/io_num_text.c
index 24ef9fe..a75fda2 100644
--- a/tests/io_num_text.c
+++ b/tests/io_num_text.c
@@ -87,6 +87,7 @@ static int test_read_num (const char* file_name, const back_end_t backend) {
   // read numerical attribute from the file
   rc = trexio_read_nucleus_num(file, &num);
   assert (rc == TREXIO_SUCCESS);
+  assert (num == 12);
 
   // close current session
   rc = trexio_close(file);