diff --git a/extra/firefox/build b/extra/firefox/build
index c7bae58a..02b0465b 100755
--- a/extra/firefox/build
+++ b/extra/firefox/build
@@ -40,7 +40,7 @@ mv -f _ "$_f"
 export PATH="$PWD/junk/bin:$PATH"
 
 # If using libc++, CXXSTDLIB needs to be set manually.
-case $("${CC:-cc}" -print-file-name=libc++.so) in */*)
+case $("$CC" -print-file-name=libc++.so) in */*)
     export CXXSTDLIB=c++
 esac