diff --git a/main.c b/main.c
index 1c46520..8c9d2b4 100644
--- a/main.c
+++ b/main.c
@@ -350,6 +350,9 @@ static void decompress_file(void)
 			failure("Inadequate free space to decompress file, use -f to override.\n");
 	}
 
+	if (unlikely(posix_fallocate(fd_out, 0, expected_size)))
+		failure("Failed to fallocate fd_out in decompress_file\n");
+
 	fd_hist = open(control.outfile, O_RDONLY);
 	if (unlikely(fd_hist == -1))
 		fatal("Failed to open history file %s\n", control.outfile);