diff --git a/toolchain_scripts/gcc-i686-elf.sh b/toolchain_scripts/gcc-i686-elf.sh
index 61800f7d2..4ac0db410 100755
--- a/toolchain_scripts/gcc-i686-elf.sh
+++ b/toolchain_scripts/gcc-i686-elf.sh
@@ -35,7 +35,7 @@ HOMEBREW_LIBS="--with-gmp=/opt/homebrew --with-mpc=/opt/homebrew --with-mpfr=/op
 
 ADDONS=""
 
-if [ ! -z "$USE_BREW_LIBS" ]; then
+if [ ! -z ${USE_BREW_LIBS+x} ]; then
     ADDONS="$HOMEBREW_LIBS $ADDONS"
 fi
 
diff --git a/toolchain_scripts/gcc-x86_64-elf.sh b/toolchain_scripts/gcc-x86_64-elf.sh
index 774ddda02..ccb0ef897 100755
--- a/toolchain_scripts/gcc-x86_64-elf.sh
+++ b/toolchain_scripts/gcc-x86_64-elf.sh
@@ -35,7 +35,7 @@ HOMEBREW_LIBS="--with-gmp=/opt/homebrew --with-mpc=/opt/homebrew --with-mpfr=/op
 
 ADDONS=""
 
-if [ ! -z "$USE_BREW_LIBS" ]; then
+if [ ! -z ${USE_BREW_LIBS+x} ]; then
     ADDONS="$HOMEBREW_LIBS $ADDONS"
 fi