diff --git a/libraries/tests/rtos/mbed/basic/main.cpp b/libraries/tests/rtos/mbed/basic/main.cpp
index eeecd160a5..8cd33bd692 100644
--- a/libraries/tests/rtos/mbed/basic/main.cpp
+++ b/libraries/tests/rtos/mbed/basic/main.cpp
@@ -1,6 +1,12 @@
 #include "mbed.h"
 #include "rtos.h"
 
+void print_char(char c = '*')
+{
+    printf("%c", c);
+    fflush(stdout);
+}
+
 DigitalOut led1(LED1);
 DigitalOut led2(LED2);
 
@@ -8,12 +14,13 @@ void led2_thread(void const *argument) {
     while (true) {
         led2 = !led2;
         Thread::wait(1000);
+        print_char();
     }
 }
 
 int main() {
     Thread thread(led2_thread);
-    
+
     while (true) {
         led1 = !led1;
         Thread::wait(500);
diff --git a/libraries/tests/rtos/mbed/file/main.cpp b/libraries/tests/rtos/mbed/file/main.cpp
index 56d328bb59..dd08557142 100644
--- a/libraries/tests/rtos/mbed/file/main.cpp
+++ b/libraries/tests/rtos/mbed/file/main.cpp
@@ -8,42 +8,67 @@ DigitalOut led2(LED2);
 #define SIZE 120
 
 void sd_thread(void const *argument) {
+    const char *FILE_NAME = "/sd/out.txt";
+
 #if defined(TARGET_KL25Z)
     SDFileSystem sd(PTD2, PTD3, PTD1, PTD0, "sd");
 #else
     SDFileSystem sd(p11, p12, p13, p14, "sd");
 #endif
-    FILE *f = fopen("/sd/out.txt", "w");
-    
-    // allocate buffers
-    uint8_t data_written[SIZE];
-    uint8_t data_read[SIZE];
-    
-    // fill data_written buffer with random data
-    // write these data into the file
-    printf("written: [");
-    for (int i = 0; i < SIZE; i++) {
-        data_written[i] = rand() % 0xff;
-        fprintf(f, "%c", data_written[i]);
-        printf("%d ", data_written[i]);
+
+    // Allocate data buffers
+    uint8_t data_written[SIZE] = {0};
+    uint8_t data_read[SIZE] = {0};
+
+    {
+        // fill data_written buffer with random data
+        FILE *f = fopen(FILE_NAME, "w");
+        if (f) {
+            // write these data into the file
+            printf("Writing %d bytes to file:\r\n", SIZE);
+            for (int i = 0; i < SIZE; i++) {
+                data_written[i] = rand() % 0xff;
+                fprintf(f, "%c", data_written[i]);
+                printf("%02X ", data_written[i]);
+                if (i && ((i % 20) == 19)) {
+                    printf("\r\n");
+                }
+            }
+            fclose(f);
+        }
+        else {
+            notify_completion(false);
+            return;
+        }
     }
-    printf("]\r\nclosing\r\n");
-    fclose(f);
-    
-    // read back the data from the file and store them in data_read
-    f = fopen("/sd/out.txt", "r");
-    printf("read: [");
-    for (int i=0; i<SIZE; i++) {
-        data_read[i] = fgetc(f);
-        printf("%d ", data_read[i]);
+    printf("\r\n\r\n");
+
+    {
+        // read back the data from the file and store them in data_read
+        FILE *f = fopen(FILE_NAME, "r");
+        if (f) {
+            printf("Reading %d bytes from file:\r\n", SIZE);
+            for (int i = 0; i < SIZE; i++) {
+                data_read[i] = fgetc(f);
+                printf("%02X ", data_read[i]);
+                if (i && ((i % 20) == 19)) {
+                    printf("\r\n");
+                }
+            }
+            fclose(f);
+        }
+        else {
+            notify_completion(false);
+            return;
+        }
     }
-    printf("]\r\nclosing\r\n");
-    fclose(f);
-    
+    printf("\r\nDone.\r\n");
+
     // check that the data written == data read
     for (int i = 0; i < SIZE; i++) {
         if (data_written[i] != data_read[i]) {
             notify_completion(false);
+            return;
         }
     }
     notify_completion(true);
@@ -51,7 +76,7 @@ void sd_thread(void const *argument) {
 
 int main() {
     Thread t(sd_thread, NULL, osPriorityNormal, (DEFAULT_STACK_SIZE * 2.25));
-    
+
     while (true) {
         led2 = !led2;
         Thread::wait(1000);