diff --git a/src/parsley.cpp b/src/parsley.cpp
index e9d49bd..584d7ac 100644
--- a/src/parsley.cpp
+++ b/src/parsley.cpp
@@ -5725,7 +5725,8 @@ void APar_MergeTempFile(FILE *dest_file,
       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, max_buffer, 1, dest_file);
@@ -5740,7 +5741,8 @@ void APar_MergeTempFile(FILE *dest_file,
       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, src_file_size - file_pos, 1, dest_file);