# "unrecognized argument to ‘-flto=’ option" error

**URL:** https://discourse.cmake.org/t/unrecognized-argument-to-flto-option-error/11480
**Category:** Usage
**Created:** [August 18, 2024, 5:00pm UTC](https://discourse.cmake.org/t/unrecognized-argument-to-flto-option-error/11480 "2024-08-18T17:00:49Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![syglon](https://discourse.cmake.org/letter_avatar_proxy/v4/letter/s/4491bb/32.png) [@syglon](https://discourse.cmake.org/u/syglon)
#### Post date: [August 18, 2024, 5:00pm UTC](https://discourse.cmake.org/t/unrecognized-argument-to-flto-option-error/11480/1 "2024-08-18T17:00:49Z")

</div>

I am currently trying to install a project on my Linux machine. My CMake version is 3.22.1. When I type ‘make’ command I am getting this error:

```auto
unrecognized argument to ‘-flto=’ option: ‘auto -ffat-lto-objects -flto=auto’

```

I found out these two lines in the CMakeCache.txt file:

```auto
//MPI C compilation options
MPI_C_COMPILE_OPTIONS:STRING=-flto=auto;-ffat-lto-objects;-flto=auto

```

I don’t think that there exists any problem with the installation of MPI. And when i comment out these two lines I am getting so many errors containing messages like this:

```auto
undefined reference to 'ompi_mpi_*'

```

Any kind of help is appreciated. Thanks for your time.