diff --git a/build_tools.sh b/build_tools.sh
index f4656e2d8..824ed025b 100755
--- a/build_tools.sh
+++ b/build_tools.sh
@@ -1,8 +1,8 @@
 #!/bin/sh
-make -C tools/gbagfx CXX=${1:=g++}
-make -C tools/scaninc CXX=${1:=g++}
-make -C tools/preproc CXX=${1:=g++}
-make -C tools/bin2c CXX=${1:=g++}
-make -C tools/rsfont CXX=${1:=g++}
-make -C tools/aif2pcm CXX=${1:=g++}
-make -C tools/ramscrgen CXX=${1:=g++}
+make -C tools/gbagfx CXX=${1:-g++}
+make -C tools/scaninc CXX=${1:-g++}
+make -C tools/preproc CXX=${1:-g++}
+make -C tools/bin2c CXX=${1:-g++}
+make -C tools/rsfont CXX=${1:-g++}
+make -C tools/aif2pcm CXX=${1:-g++}
+make -C tools/ramscrgen CXX=${1:-g++}