diff --git a/build_file.cpp b/build_file.cpp
index ea645a3..9c56861 100644
--- a/build_file.cpp
+++ b/build_file.cpp
@@ -6,9 +6,8 @@ int ReturnValue = 0;
 int Main() {
     Strs cc = CMDLine.get("cc"_s, ON_WINDOWS("cl"_s) ON_MAC("clang"_s) ON_LINUX("gcc"_s));
     Strs files = ListDir("../tests");
-    CompileFiles(cc, {"../tests/main_core_as_header.cpp", "../core_library/core.c"});
     For(files) {
-        if (S8_Find(it, "test_"_s)) {
+        if (S8_Seek(it, "test_"_s)) {
             CompileFiles(cc, it);
         }
     }
diff --git a/build_tool/build_lib.cpp b/build_tool/build_lib.cpp
index ae415e1..9699c32 100644
--- a/build_tool/build_lib.cpp
+++ b/build_tool/build_lib.cpp
@@ -224,7 +224,7 @@ int main(int argc, char **argv) {
         S8_String it = S8_MakeFromChar(argv[i]);
 
         int64_t idx = 0;
-        if (S8_Find(it, "="_s, 0, &idx)) {
+        if (S8_Seek(it, "="_s, 0, &idx)) {
             S8_String key = S8_GetPrefix(it, idx);
             S8_String value = S8_Skip(it, idx + 1);
             if (key.len == 0) ReportError(it);
diff --git a/build_tool/build_main.cpp b/build_tool/build_main.cpp
index d769446..faea11c 100644
--- a/build_tool/build_main.cpp
+++ b/build_tool/build_main.cpp
@@ -24,10 +24,10 @@ int main(int argument_count, char **arguments) {
     SRC_InitCache(Perm, cache_filename);
 
     // Search for build file in the project directory
-    S8_String build_file = {0};
+    S8_String build_file = {};
     {
         for (OS_FileIter it = OS_IterateFiles(Perm, S8_Lit("..")); OS_IsValid(it); OS_Advance(&it)) {
-            if (S8_Find(it.filename, S8_Lit("build_file.c"), S8_IgnoreCase)) {
+            if (S8_Seek(it.filename, S8_Lit("build_file.c"), S8_IgnoreCase)) {
                 build_file = it.absolute_path;
             }
         }
diff --git a/core_library/core.h b/core_library/core.h
index a50bb14..0521cc3 100644
--- a/core_library/core.h
+++ b/core_library/core.h
@@ -3,8 +3,8 @@
 #include "../standalone_libraries/stb_sprintf.h"
 #include "../standalone_libraries/io.h"
 #include "../standalone_libraries/arena.h"
-#include "../standalone_libraries/string.h"
 #include "../standalone_libraries/unicode.h"
+#include "../standalone_libraries/string.h"
 #include "../standalone_libraries/hash.h"
 #include "../standalone_libraries/linked_list.h"
 #include "../standalone_libraries/regex.h"
diff --git a/core_library/filesystem.c b/core_library/filesystem.c
index 00bc33a..a0260a7 100644
--- a/core_library/filesystem.c
+++ b/core_library/filesystem.c
@@ -678,7 +678,7 @@ OS_API bool OS_ExpandIncludesList(MA_Arena *arena, S8_List *out, S8_String filep
     S8_String include = S8_Lit("#include \"");
     for (;;) {
         int64_t idx = -1;
-        if (S8_Find(c, include, 0, &idx)) {
+        if (S8_Seek(c, include, 0, &idx)) {
             S8_String str_to_add = S8_GetPrefix(c, idx);
             S8_AddNode(arena, out, str_to_add);
             S8_String save = c;
@@ -706,8 +706,8 @@ OS_API bool OS_ExpandIncludesList(MA_Arena *arena, S8_List *out, S8_String filep
 }
 
 OS_API S8_String OS_ExpandIncludes(MA_Arena *arena, S8_String filepath) {
-    S8_List out = {0};
-    S8_String result = {0};
+    S8_List out = S8_MakeEmptyList();
+    S8_String result = S8_MakeEmpty();
     MA_ScratchScope(s) {
         OS_ExpandIncludesList(s.arena, &out, filepath);
         result = S8_Merge(arena, out);
diff --git a/core_library/filesystem.h b/core_library/filesystem.h
index ba04b0e..a894443 100644
--- a/core_library/filesystem.h
+++ b/core_library/filesystem.h
@@ -1,11 +1,7 @@
 // Quick and dirty filesystem operations
 
 #ifndef OS_API
-    #ifdef __cplusplus
-        #define OS_API extern "C"
-    #else
-        #define OS_API
-    #endif
+    #define OS_API
 #endif
 
 typedef enum OS_Result {
diff --git a/standalone_libraries/string.c b/standalone_libraries/string.c
index 010f3c6..7ea643a 100644
--- a/standalone_libraries/string.c
+++ b/standalone_libraries/string.c
@@ -258,7 +258,7 @@ S8_API S8_String S8_ToUpperCase(S8_Allocator allocator, S8_String s) {
     return copy;
 }
 
-S8_API bool S8_Find(S8_String string, S8_String find, S8_FindFlag flags, int64_t *index_out) {
+S8_API bool S8_Seek(S8_String string, S8_String find, S8_FindFlag flags, int64_t *index_out) {
     bool ignore_case = flags & S8_FindFlag_IgnoreCase ? true : false;
     bool result = false;
     if (flags & S8_FindFlag_MatchFindLast) {
@@ -288,12 +288,18 @@ S8_API bool S8_Find(S8_String string, S8_String find, S8_FindFlag flags, int64_t
     return result;
 }
 
+S8_API int64_t S8_Find(S8_String string, S8_String find, S8_FindFlag flag) {
+    int64_t result = -1;
+    S8_Seek(string, find, flag, &result);
+    return result;
+}
+
 S8_API S8_List S8_Split(S8_Allocator allocator, S8_String string, S8_String find, S8_SplitFlag flags) {
     S8_List result = S8_MakeEmptyList();
     int64_t index = 0;
 
     S8_FindFlag find_flag = flags & S8_SplitFlag_IgnoreCase ? S8_FindFlag_IgnoreCase : S8_FindFlag_None;
-    while (S8_Find(string, find, find_flag, &index)) {
+    while (S8_Seek(string, find, find_flag, &index)) {
         S8_String before_match = S8_Make(string.str, index);
         S8_AddNode(allocator, &result, before_match);
         if (flags & S8_SplitFlag_SplitInclusive) {
@@ -350,7 +356,7 @@ S8_API S8_List S8_FindAll(S8_Allocator allocator, S8_String string, S8_String fi
     int64_t index = 0;
 
     S8_FindFlag find_flag = ignore_case ? S8_FindFlag_IgnoreCase : 0;
-    while (S8_Find(string, find, find_flag, &index)) {
+    while (S8_Seek(string, find, find_flag, &index)) {
         S8_String match = S8_Make(string.str + index, find.len);
         S8_AddNode(allocator, &result, match);
         string = S8_Skip(string, index + find.len);
@@ -360,20 +366,20 @@ S8_API S8_List S8_FindAll(S8_Allocator allocator, S8_String string, S8_String fi
 
 S8_API S8_String S8_ChopLastSlash(S8_String s) {
     S8_String result = s;
-    S8_Find(s, S8_Lit("/"), S8_FindFlag_MatchFindLast, &result.len);
+    S8_Seek(s, S8_Lit("/"), S8_FindFlag_MatchFindLast, &result.len);
     return result;
 }
 
 S8_API S8_String S8_ChopLastPeriod(S8_String s) {
     S8_String result = s;
-    S8_Find(s, S8_Lit("."), S8_FindFlag_MatchFindLast, &result.len);
+    S8_Seek(s, S8_Lit("."), S8_FindFlag_MatchFindLast, &result.len);
     return result;
 }
 
 S8_API S8_String S8_SkipToLastSlash(S8_String s) {
     int64_t pos;
     S8_String result = s;
-    if (S8_Find(s, S8_Lit("/"), S8_FindFlag_MatchFindLast, &pos)) {
+    if (S8_Seek(s, S8_Lit("/"), S8_FindFlag_MatchFindLast, &pos)) {
         result = S8_Skip(result, pos + 1);
     }
     return result;
@@ -382,7 +388,7 @@ S8_API S8_String S8_SkipToLastSlash(S8_String s) {
 S8_API S8_String S8_SkipToLastPeriod(S8_String s) {
     int64_t pos;
     S8_String result = s;
-    if (S8_Find(s, S8_Lit("."), S8_FindFlag_MatchFindLast, &pos)) {
+    if (S8_Seek(s, S8_Lit("."), S8_FindFlag_MatchFindLast, &pos)) {
         result = S8_Skip(result, pos + 1);
     }
     return result;
diff --git a/standalone_libraries/string.h b/standalone_libraries/string.h
index d1bc5b6..a622f07 100644
--- a/standalone_libraries/string.h
+++ b/standalone_libraries/string.h
@@ -4,11 +4,7 @@
 #include <stdbool.h>
 
 #ifndef S8_API
-    #ifdef __cplusplus
-        #define S8_API extern "C"
-    #else
-        #define S8_API
-    #endif
+    #define S8_API
 #endif
 
 #ifdef __cplusplus
@@ -30,6 +26,35 @@ S8_API int64_t S8_Length(char *string);
 struct S8_String {
     char *str;
     int64_t len;
+#if defined(__cplusplus)
+    S8_String() = default;
+    S8_String(char *s) : str(s), len(S8_Length(s)) {}
+    S8_String(char *s, int64_t l) : str(s), len(l) {}
+    S8_String(const char *s) : str((char *)s), len(S8_Length((char *)s)) {}
+    S8_String(const char *s, int64_t l) : str((char *)s), len(l) {}
+    #if defined(UTF_HEADER)
+    struct Iter {
+        UTF8_Iter i;
+
+        Iter operator++(int) {
+            Iter ret = *this;
+            UTF8_Advance(&i);
+            return ret;
+        }
+
+        Iter &operator++() {
+            UTF8_Advance(&i);
+            return *this;
+        }
+
+        friend bool operator!=(const Iter &a, const Iter &b) { return a.i.item != b.i.item; }
+        UTF8_Iter &operator*() { return i; }
+    };
+
+    Iter begin() { return {UTF8_IterateEx(str, (int)len)}; }
+    Iter end() { return {}; }
+    #endif // UTF_HEADER
+#endif     // __cplusplus
 };
 
 struct S8_Node {
@@ -44,8 +69,6 @@ struct S8_List {
     S8_Node *last;
 };
 
-const int S8_IgnoreCase = true;
-
 typedef int S8_FindFlag;
 enum {
     S8_FindFlag_None = 0,
@@ -60,6 +83,8 @@ enum {
     S8_SplitFlag_SplitInclusive = 2,
 };
 
+const bool S8_IgnoreCase = true;
+
 #if defined(__has_attribute)
     #if __has_attribute(format)
         #define S8__PrintfFormat(fmt, va) __attribute__((format(printf, fmt, va)))
@@ -83,12 +108,6 @@ enum {
 
 #define S8_For(it, x) for (S8_Node *it = (x).first; it; it = it->next)
 
-#if defined(__cplusplus)
-S8_API bool S8_AreEqual(S8_String a, S8_String b, unsigned ignore_case);
-inline bool operator==(S8_String a, S8_String b) { return S8_AreEqual(a, b, false); }
-inline S8_String operator""_s(const char *str, size_t size) { return {(char *)str, (int64_t)size}; }
-#endif
-
 S8_API char CHAR_ToLowerCase(char a);
 S8_API char CHAR_ToUpperCase(char a);
 S8_API bool CHAR_IsWhitespace(char w);
@@ -111,7 +130,8 @@ S8_API S8_String S8_Trim(S8_String string);
 S8_API S8_String S8_TrimEnd(S8_String string);
 S8_API S8_String S8_ToLowerCase(S8_Allocator allocator, S8_String s);
 S8_API S8_String S8_ToUpperCase(S8_Allocator allocator, S8_String s);
-S8_API bool S8_Find(S8_String string, S8_String find, S8_FindFlag flags S8_IF_CPP(= S8_FindFlag_None), int64_t *index_out S8_IF_CPP(= 0));
+S8_API bool S8_Seek(S8_String string, S8_String find, S8_FindFlag flags S8_IF_CPP(= S8_FindFlag_None), int64_t *index_out S8_IF_CPP(= 0));
+S8_API int64_t S8_Find(S8_String string, S8_String find, S8_FindFlag flags S8_IF_CPP(= S8_FindFlag_None));
 S8_API S8_String S8_ChopLastSlash(S8_String s);
 S8_API S8_String S8_ChopLastPeriod(S8_String s);
 S8_API S8_String S8_SkipToLastSlash(S8_String s);
@@ -128,7 +148,7 @@ S8_API S8_String S8_FormatV(S8_Allocator allocator, const char *str, va_list arg
 S8_API S8_String S8_Format(S8_Allocator allocator, const char *str, ...) S8__PrintfFormat(2, 3);
 
 S8_API S8_List S8_Split(S8_Allocator allocator, S8_String string, S8_String find, S8_SplitFlag flags S8_IF_CPP(= S8_SplitFlag_None));
-S8_API S8_String S8_MergeWithSeparator(S8_Allocator allocator, S8_List list, S8_String separator S8_IF_CPP(= " "_s));
+S8_API S8_String S8_MergeWithSeparator(S8_Allocator allocator, S8_List list, S8_String separator S8_IF_CPP(= S8_Lit(" ")));
 S8_API S8_String S8_Merge(S8_Allocator allocator, S8_List list);
 S8_API S8_String S8_ReplaceAll(S8_Allocator allocator, S8_String string, S8_String replace, S8_String with, bool ignore_case S8_IF_CPP(= false));
 S8_API S8_List S8_FindAll(S8_Allocator allocator, S8_String string, S8_String find, bool ignore_case S8_IF_CPP(= false));
@@ -144,3 +164,9 @@ S8_API S8_List S8_ConcatLists(S8_Allocator allocator, S8_List a, S8_List b);
 S8_API S8_Node *S8_AddNode(S8_Allocator allocator, S8_List *list, S8_String string);
 S8_API S8_Node *S8_Add(S8_Allocator allocator, S8_List *list, S8_String string);
 S8_API S8_String S8_AddF(S8_Allocator allocator, S8_List *list, const char *str, ...) S8__PrintfFormat(3, 4);
+
+#if defined(__cplusplus)
+inline S8_String operator""_s(const char *str, size_t size) { return {(char *)str, (int64_t)size}; }
+inline bool operator==(S8_String a, S8_String b) { return S8_AreEqual(a, b, 0); }
+inline bool operator!=(S8_String a, S8_String b) { return !S8_AreEqual(a, b, 0); }
+#endif
diff --git a/standalone_libraries/unicode.h b/standalone_libraries/unicode.h
index 9b360dd..18308ca 100644
--- a/standalone_libraries/unicode.h
+++ b/standalone_libraries/unicode.h
@@ -1,4 +1,5 @@
 #pragma once
+#define UTF_HEADER
 #include <stdint.h>
 typedef struct UTF32_Result UTF32_Result;
 typedef struct UTF8_Result UTF8_Result;
diff --git a/tests/1test_string.cpp b/tests/1test_string.cpp
index 6f1b662..459f3a4 100644
--- a/tests/1test_string.cpp
+++ b/tests/1test_string.cpp
@@ -1,10 +1,14 @@
 #include "../core_library/core.c"
 
 int main() {
-    MA_Scratch scratch;
-    for (OS_FileIter it = OS_IterateFiles(scratch, "../"_s); OS_IsValid(it); OS_Advance(&it)) {
-        IO_Printf("is_directory: %d\n", it.is_directory);
-        IO_Printf("absolute_path: %.*s\n", S8_Expand(it.absolute_path));
-        IO_Printf("relative_path: %.*s\n", S8_Expand(it.relative_path));
+    S8_String s = "mrówka";
+
+    bool found_two_byte = false;
+    For(s) {
+        if (it.utf8_codepoint_byte_size == 2) {
+            found_two_byte = true;
+            IO_Assert(it.i == 2);
+        }
     }
+    IO_Assert(found_two_byte);
 }
\ No newline at end of file
diff --git a/tests/main_core_as_header.cpp b/tests/main_core_as_header.cpp
deleted file mode 100644
index ed16a52..0000000
--- a/tests/main_core_as_header.cpp
+++ /dev/null
@@ -1,8 +0,0 @@
-#include "../core_library/core.h"
-
-int main() {
-    MA_Arena arena = {};
-    int *a = MA_PushStruct(&arena, int);
-    *a = 10;
-    return 0;
-}
\ No newline at end of file
diff --git a/tests/test_filesystem.c b/tests/test_filesystem.c
index 4b375a3..bd28bae 100644
--- a/tests/test_filesystem.c
+++ b/tests/test_filesystem.c
@@ -67,11 +67,21 @@ int main() {
         IO_Assert(OS_IsAbsolute(work_path));
         IO_Assert(OS_IsAbsolute(abs_path));
 
-        IO_Assert(S8_Find(exe_path, S8_Lit("/test_filesystem"), 0, 0));
-        IO_Assert(S8_Find(exe_path, S8_Lit("/build"), 0, 0));
-        IO_Assert(S8_Find(dir_path, S8_Lit("/build"), 0, 0));
-        IO_Assert(S8_Find(work_path, S8_Lit("/build"), 0, 0));
-        IO_Assert(S8_Find(abs_path, S8_Lit("/tests/data"), 0, 0));
-        IO_Assert(!S8_Find(abs_path, S8_Lit("../"), 0, 0));
+        IO_Assert(S8_Seek(exe_path, S8_Lit("/test_filesystem"), 0, 0));
+        IO_Assert(S8_Seek(exe_path, S8_Lit("/build"), 0, 0));
+        IO_Assert(S8_Seek(dir_path, S8_Lit("/build"), 0, 0));
+        IO_Assert(S8_Seek(work_path, S8_Lit("/build"), 0, 0));
+        IO_Assert(S8_Seek(abs_path, S8_Lit("/tests/data"), 0, 0));
+        IO_Assert(!S8_Seek(abs_path, S8_Lit("../"), 0, 0));
+    }
+
+    {
+        for (OS_FileIter it = OS_IterateFiles(&arena, S8_Lit("..")); OS_IsValid(it); OS_Advance(&it)) {
+            if (it.is_directory) {
+                IO_Assert(it.absolute_path.str[it.absolute_path.len - 1] == '/');
+            }
+            IO_Assert(!S8_Seek(it.absolute_path, S8_Lit(".."), 0, 0));
+            IO_Assert(S8_Seek(it.relative_path, S8_Lit(".."), 0, 0));
+        }
     }
 }
\ No newline at end of file