diff --git a/extra/wpa_supplicant/build b/extra/wpa_supplicant/build
index fcb6c61b..ad25afb7 100755
--- a/extra/wpa_supplicant/build
+++ b/extra/wpa_supplicant/build
@@ -13,6 +13,8 @@ export LDFLAGS="-L$PWD/libnl"
 (
     cd libnl
 
+    # CFLAGS must expand to individual arguments.
+    # shellcheck disable=2086
     $CC $CFLAGS $CPPFLAGS -c ./*.c
     ar rc libnl-tiny.a ./*.o
 )