diff --git a/include/tlibc/base64.h b/include/tlibc/base64.h
index e71cc88..e1d371d 100644
--- a/include/tlibc/base64.h
+++ b/include/tlibc/base64.h
@@ -20,4 +20,4 @@ u32 base64_decodedSize(const char* src, u32 src_size);
 /// @param src_size size of data to decode. Must be a multiple of 4 for valid base64 data.
 /// @param dst buffer of size base64_decodedSize(src, src_size)
 /// @return number of decoded characters or 0 on error
-u32 base64_decode(const u8* src, u32 src_size, u8* dst);
+u32 base64_decode(const char* src, u32 src_size, u8* dst);
diff --git a/include/tlibc/collections/Array.h b/include/tlibc/collections/Array.h
index d699ed1..9aa6812 100755
--- a/include/tlibc/collections/Array.h
+++ b/include/tlibc/collections/Array.h
@@ -35,6 +35,3 @@ static inline Array_ Array_copy(Array_ src){
 
 #define Array_len(AR, T) ((AR)->size / sizeof(T))
 #define Array_memset(A, VAL) memset((A)->data, VAL, (A)->size)
-
-#define str_castTo_Array(S) Array_construct_size((S).data, (S).size)
-#define Array_castTo_str(S, IS_ZERO_TERMINATED) str_construct((S).data, (S).size, IS_ZERO_TERMINATED)
diff --git a/include/tlibc/string/str.h b/include/tlibc/string/str.h
index 509b03f..866961d 100755
--- a/include/tlibc/string/str.h
+++ b/include/tlibc/string/str.h
@@ -20,6 +20,14 @@ static inline str str_from_cstr(cstr s_ptr){
     return str_construct((void*)s_ptr, strlen(s_ptr), true);
 }
 
+static inline Array_ str_castTo_Array(str s) {
+    return Array_construct_size(s.data, s.size);
+}
+
+static inline str Array_castTo_str(Array_ a, bool isZeroTerminated) {
+    return str_construct(a.data, a.size, isZeroTerminated);
+}
+
 static const str str_null = str_construct(NULL, 0, 0);
 
 /// copies src content to new string and adds \0 at the end
diff --git a/src/base64.c b/src/base64.c
index bac1765..7eae33d 100644
--- a/src/base64.c
+++ b/src/base64.c
@@ -61,7 +61,7 @@ static int b64inverse[] = {
 	43, 44, 45, 46, 47, 48, 49, 50, 51
 };
 
-u32 base64_decode(const u8* src, u32 src_size, u8* dst){
+u32 base64_decode(const char* src, u32 src_size, u8* dst){
     // incomplete src
     if(src_size % 4 != 0)
         return 0;
diff --git a/src/string/StringBuilder.c b/src/string/StringBuilder.c
index b32bdd3..9ef10c2 100755
--- a/src/string/StringBuilder.c
+++ b/src/string/StringBuilder.c
@@ -6,7 +6,8 @@ void StringBuilder_destroy(StringBuilder* b){
 }
 
 str StringBuilder_getStr(StringBuilder* b){
-    List_push(&b->buffer, u8, '\0');
+    if(b->buffer.size == 0 || ((char*)b->buffer.data)[b->buffer.size - 1] != '\0')
+        List_push(&b->buffer, u8, '\0');
     str result = str_construct((char*)b->buffer.data, b->buffer.size - 1, true);
     return result;
 }