--- src/parsley.cpp
+++ src/parsley.cpp
@@ -4585,10 +4585,11 @@
 #if defined(_MSC_VER)
 			fpos_t file_offset = dest_position + file_pos;
 #elif defined(__GLIBC__)
-      fpos_t file_offset = {0};
+			fpos_t file_offset = {0};
 			file_offset.__pos = dest_position + file_pos;
 #else
-			off_t file_offset = dest_position + file_pos;
+			fpos_t file_offset = {0};
+			*(uint64_t*) &file_offset = dest_position + file_pos;
 #endif
 			fsetpos(dest_file, &file_offset);
 			fwrite(buffer, (size_t)max_buffer, 1, dest_file);
@@ -4601,10 +4601,11 @@
 #if defined(_MSC_VER)
 			fpos_t file_offset = dest_position + file_pos;
 #elif defined(__GLIBC__)
-      fpos_t file_offset = {0};
+			fpos_t file_offset = {0};
 			file_offset.__pos = dest_position + file_pos;
 #else
-			off_t file_offset = dest_position + file_pos;
+			fpos_t file_offset = {0};
+			*(uint64_t*) &file_offset = dest_position + file_pos;
 #endif
 			fsetpos(dest_file, &file_offset );
 			fwrite(buffer, (size_t)(src_file_size - file_pos), 1, dest_file);