diff --git a/axl_string_test.c b/axl_string_test.c
index 6e38cae..30fe158 100644
--- a/axl_string_test.c
+++ b/axl_string_test.c
@@ -6,10 +6,6 @@
 #include "axl_koan.h"
 #include "axl_memory.h"
 
-/* ------------------------------------------------------------------ */
-/* axl_strlen */
-/* ------------------------------------------------------------------ */
-
 KOAN(strlen_empty)
 {
     i8* s = (i8*)"";
@@ -28,10 +24,6 @@ KOAN(strlen_with_special_chars)
     ASSERT_UINT_EQ(12, axl_strlen(s));
 }
 
-/* ------------------------------------------------------------------ */
-/* axl_strcpy */
-/* ------------------------------------------------------------------ */
-
 KOAN(strcpy_basic)
 {
     i8* src = (i8*)"test";
@@ -59,10 +51,6 @@ KOAN(strcpy_empty)
     axl_free(dst);
 }
 
-/* ------------------------------------------------------------------ */
-/* axl_strncpy */
-/* ------------------------------------------------------------------ */
-
 KOAN(strncpy_exact)
 {
     i8* src = (i8*)"hello";
@@ -103,10 +91,6 @@ KOAN(strncpy_pads_with_nulls)
     axl_free(dst);
 }
 
-/* ------------------------------------------------------------------ */
-/* axl_strcat */
-/* ------------------------------------------------------------------ */
-
 KOAN(strcat_basic)
 {
     i8* dst = (i8*)axl_malloc(20);
@@ -133,10 +117,6 @@ KOAN(strcat_to_empty)
     axl_free(dst);
 }
 
-/* ------------------------------------------------------------------ */
-/* axl_strncat */
-/* ------------------------------------------------------------------ */
-
 KOAN(strncat_full)
 {
     i8* dst = (i8*)axl_malloc(20);
@@ -177,10 +157,6 @@ KOAN(strncat_always_null_terminates)
     axl_free(dst);
 }
 
-/* ------------------------------------------------------------------ */
-/* axl_strcmp */
-/* ------------------------------------------------------------------ */
-
 KOAN(strcmp_equal)
 {
     i8* s1 = (i8*)"hello";
@@ -223,9 +199,35 @@ KOAN(strcmp_first_empty)
     ASSERT_TRUE(axl_strcmp(s1, s2) < 0);
 }
 
-/* ------------------------------------------------------------------ */
-/* Main */
-/* ------------------------------------------------------------------ */
+KOAN(strlen_null) 
+{ 
+    ASSERT_UINT_EQ(0, axl_strlen(NULL)); 
+}
+
+KOAN(strcpy_null_dst) 
+{ 
+    i8 buf[10]; 
+    ASSERT_PTR_EQ(buf, axl_strcpy(buf, NULL));
+}
+
+KOAN(strcpy_null_src) 
+{ 
+    ASSERT_NULL(axl_strcpy(NULL, (const i8*)"test")); 
+}
+
+KOAN(strncpy_zero_n) 
+{
+    i8 dst[10] = {'w'};
+    axl_strncpy(dst, (const i8*)"test", 0);
+    ASSERT_INT_EQ('w', dst[0]);
+}
+
+KOAN(strncat_zero_n) 
+{
+    i8 dst[10] = "hi";
+    axl_strncat(dst, (const i8*)"world", 0);
+    ASSERT_STR_EQ("hi", (char*)dst);
+}
 
 int main(void)
 {