diff --git a/src/SPC/builder/unix/library/ncurses.php b/src/SPC/builder/unix/library/ncurses.php
index 27725c3d..31e61b1e 100644
--- a/src/SPC/builder/unix/library/ncurses.php
+++ b/src/SPC/builder/unix/library/ncurses.php
@@ -16,6 +16,7 @@ trait ncurses
 
         UnixAutoconfExecutor::create($this)
             ->appendEnv([
+                'CFLAGS' => '-std=gnu99',
                 'LDFLAGS' => SPCTarget::isStatic() ? '-static' : '',
             ])
             ->configure(