--- a/tests.c	Tue Feb 16 21:28:00 2016 +0200
+++ b/tests.c	Tue Feb 16 22:00:54 2016 +0200
@@ -14,52 +14,52 @@
     int ret1, ret2, ret = 0;
     va_list tmp;
 
-    printf("th_vsnprintf(%" TH_PRIu_SIZE_T ", '%s'): ", len, fmt);
+    memset(buf1, 0xe5, SET_BUF_SIZE+2); buf1[SET_BUF_SIZE+1] = 0;
+    memset(buf2, 0xe5, SET_BUF_SIZE+2); buf2[SET_BUF_SIZE+1] = 0;
 
     va_copy(tmp, ap);
 
     ret1 = th_vsnprintf(buf1, len, fmt, ap);
     ret2 = vsnprintf(buf2, len, fmt, tmp);
 
+
     if (ret1 != ret2)
     {
-        printf("ret mismatch (%d != %d)\n", ret1, ret2);
+        THPRINT(1, "  retval mismatch (%d != %d)\n", ret1, ret2);
         ret = -1;
     }
 
     if (strcmp(buf1, buf2))
     {
-        printf("result mismatch:\n'%s' VS\n'%s'\n", buf1, buf2);
+        THPRINT(1, "  result mismatch:\n'%s' VS\n'%s'\n", buf1, buf2);
+        ret = -2;
+    }
+
+    if ((unsigned char) buf1[len] != 0xe5)
+    {
+        THPRINT(1, "  buffer #1 overflow, sentinel 0x%02x\n", buf1[len]);
         ret = -2;
     }
 
+    if ((unsigned char) buf2[len] != 0xe5)
+    {
+        THPRINT(1, "  buffer #2 overflow, sentinel 0x%02x\n", buf2[len]);
+        ret = -2;
+    }
+
+    if (ret != 0)
+        THPRINT(1, "th_vsnprintf(%" TH_PRIu_SIZE_T ", '%s'): ", len, fmt);
+
     if (ret == 0)
-        printf("OK\n");
+        THPRINT(1, "OK\n");
+
     return ret;
 }
 
 
 void test_snprintf_do(size_t len, const char *fmt, va_list ap)
 {
-    int ret;
-
-    memset(buf1, 0xe5, SET_BUF_SIZE+2); buf1[SET_BUF_SIZE+1] = 0;
-    memset(buf2, 0xe5, SET_BUF_SIZE+2); buf2[SET_BUF_SIZE+1] = 0;
-
-    ret = test_snprintf_do2(len, fmt, ap);
-
-    if ((unsigned char) buf1[len] != 0xe5)
-    {
-        printf("  buffer #1 overflow, sentinel 0x%02x\n", buf1[len]);
-        ret = -2;
-    }
-
-    if ((unsigned char) buf2[len] != 0xe5)
-    {
-        printf("  buffer #2 overflow, sentinel 0x%02x\n", buf2[len]);
-        ret = -2;
-    }
-
+    int ret = test_snprintf_do2(len, fmt, ap);
     if (ret == 0)
         passed++;
     else
@@ -70,15 +70,15 @@
 void test_snprintf(const char *fmt, ...)
 {
     va_list ap, tmp;
-    printf("----------------------------------------------\n");
+    THPRINT(1, "----------------------------------------------\n");
     va_start(ap, fmt);
     va_copy(tmp, ap); test_snprintf_do(0, fmt, tmp);
     va_copy(tmp, ap); test_snprintf_do(1, fmt, tmp);
     va_copy(tmp, ap); test_snprintf_do(2, fmt, tmp);
     va_copy(tmp, ap); test_snprintf_do(16, fmt, tmp);
     va_copy(tmp, ap); test_snprintf_do(SET_BUF_SIZE, fmt, tmp);
-    va_end(ap);
-    printf("----------------------------------------------\n");
+    va_end(ap); 
+    THPRINT(1, "----------------------------------------------\n");
 }
 
 
@@ -87,8 +87,11 @@
     (void) argc;
     (void) argv;
 
+    //
+    // Initialization
+    //
     th_init("th-test", "th-libs unit tests", "0.0.1", NULL, NULL);
-    th_verbosityLevel = 1;
+    th_verbosityLevel = 0;
 
     if (sizeof(char) != sizeof(unsigned char))
     {
@@ -98,21 +101,31 @@
 
     failed = passed = 0;
 
+    //
+    // Test series #1
+    //
+    THPRINT(0, "printf() family function tests.\n");
     int i_vals[] = { 2, 612342, -2, -612342, 0x1fff, 0x8000000, };
     char *i_fmts[] = { "%d", "%x", "%05d", "%5d", "%-5d", "%05x", "%5x", };
-    int i1, i2;
+    size_t i1, i2;
 
     for (i1 = 0; i1 < sizeof(i_vals) / sizeof(i_vals[0]); i1++)
     for (i2 = 0; i2 < sizeof(i_fmts) / sizeof(i_fmts[0]); i2++)
         test_snprintf(i_fmts[i2], i_vals);
 
-    char *s_vals[] = { "", "asdf", "xxx yyy zzz ppp fff", NULL, };
-    char *s_fmts[] = { "%s", "%2s", "%-2s", "%5s", "%-5s", "%16s", "%-16s", };
+    char *s_vals[] = { "", "asdf", "xxx yyy zzz ppp fff", NULL, "X" };
+    char *s_fmts[] = { "%s", "%2s", "%-2s", "%5s", "%-5s", "%16s", "%-16s", "%1s", "%-1s", };
 
     for (i1 = 0; i1 < sizeof(s_vals) / sizeof(s_vals[0]); i1++)
     for (i2 = 0; i2 < sizeof(s_fmts) / sizeof(s_fmts[0]); i2++)
         test_snprintf(s_fmts[i2], s_vals);
 
-    printf("%d tests failed, %d passed.\n", failed, passed);
+
+    //
+    // Print summary and exit
+    //
+    THPRINT(0, "%d tests failed, %d passed.\n",
+        failed, passed);
+
     return 0;
 }