# Selecting Compiler

**URL:** <https://discourse.slicer.org/t/selecting-compiler/6503>\
**Category:** Development\
**Created:** [April 15, 2019, 2:01pm UTC](https://discourse.slicer.org/t/selecting-compiler/6503 "2019-04-15T14:01:46Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![marcmclean](https://avatars.discourse-cdn.com/v4/letter/m/7993a0/32.png) [@marcmclean](https://discourse.slicer.org/u/marcmclean)\
**Post date:** [April 15, 2019, 2:01pm UTC](https://discourse.slicer.org/t/selecting-compiler/6503/1 "2019-04-15T14:01:46Z")

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I’m attempting to compile Slicer from source.  
The Slicer documentation states to not configure until after selecting your compiler.  
In CMake GUI, the only way I see to specify the compiler is to click the Configure button first  
and enter the compiler information. Is this the correct method?

Thank you,  
Marc McLean

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<div class="post-metadata">

**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [April 15, 2019, 3:13pm UTC](https://discourse.slicer.org/t/selecting-compiler/6503/2 "2019-04-15T15:13:15Z")

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You can add CMake variables before you configure by clicking `Add Entry`. I’ve updated the [build instructions](https://www.slicer.org/wiki/Documentation/Nightly/Developers/Build_Instructions/Configure#Windows) to make this more clear.