diff --git a/include/tlibc/errors.h b/include/tlibc/errors.h
index 12a380a..ef37432 100755
--- a/include/tlibc/errors.h
+++ b/include/tlibc/errors.h
@@ -93,4 +93,4 @@ typedef struct Result_ {
     }\
 } while(0)
 
-#define try_assert(EXPR) if(!(EXPR)) { Return RESULT_ERROR((#EXPR), false); } 
+#define try_assert(EXPR) if(!(EXPR)) { Return RESULT_ERROR(("try_assert(" #EXPR ")"), false); } 
diff --git a/include/tlibc/filesystem.h b/include/tlibc/filesystem.h
index e14d9c7..6bd57fe 100644
--- a/include/tlibc/filesystem.h
+++ b/include/tlibc/filesystem.h
@@ -62,6 +62,10 @@ Result(FILE*) file_open(cstr file_name, cstr fopen_mode);
 Result(FILE*) file_openOrCreateReadWrite(cstr file_name);
 
 bool file_exists(cstr path);
+
+///@return current position in file
+Result(i64) file_tellPos(FILE* f);
+///@return total size of file
 Result(i64) file_getSize(FILE* f);
 
 
@@ -71,6 +75,7 @@ typedef enum SeekOrigin {
     SeekOrigin_End = SEEK_END,
 } SeekOrigin;
 
+/// @brief changes current position in file 
 Result(void) file_seek(FILE* f, i64 offset, SeekOrigin origin);
 
 
diff --git a/src/filesystem/file.c b/src/filesystem/file.c
index ab64d86..930e85b 100644
--- a/src/filesystem/file.c
+++ b/src/filesystem/file.c
@@ -47,7 +47,7 @@ Result(FILE*) file_openOrCreateReadWrite(cstr file_name){
 
 
 
-Result(i64) file_getSize(FILE* f){
+Result(i64) file_tellPos(FILE* f){
     i64 r = IFWIN(_ftelli64, ftello64)(f);
     if(r < 0){
         return RESULT_ERROR_ERRNO();
@@ -64,6 +64,18 @@ Result(void) file_seek(FILE* f, i64 offset, SeekOrigin origin){
     return RESULT_VOID;
 }
 
+Result(i64) file_getSize(FILE* f){
+    Deferral(4);
+    // get current position
+    try(i64 original_pos, i, file_tellPos(f));
+    // seek to end
+    try_void(file_seek(f, 0, SeekOrigin_End));
+    try(i64 size, i, file_tellPos(f));
+    // restore original position
+    try_void(file_seek(f, original_pos, SeekOrigin_Start));
+    Return RESULT_VALUE(i, size);
+}
+
 
 Result(void) file_writeStructs(FILE* f, const void* src, u64 struct_size, u64 count){
     u64 r = fwrite(src, struct_size, count, f);