diff --git a/demo/build.sh b/demo/build.sh
index e3e2b4e..445f341 100755
--- a/demo/build.sh
+++ b/demo/build.sh
@@ -1,14 +1,15 @@
-#!/bin/bash
+#!/bin/sh
 
 OS_NAME=`uname -o 2>/dev/null || uname -s`
 
-if [ $OS_NAME == "Msys" ]; then
-    GLFLAG="-lopengl32"
-elif [ $OS_NAME == "Darwin" ]; then
-    GLFLAG="-framework OpenGL"
-else
-    GLFLAG="-lGL"
-fi
+case "$OS_NAME" in
+Msys)
+    GLFLAG="-lopengl32";;
+Darwin)
+    GLFLAG="-framework OpenGL";;
+*)
+    GLFLAG="-lGL";;
+esac
 
 CFLAGS="-I../src -Wall -std=c11 -pedantic `sdl2-config --libs` $GLFLAG -lm -O3 -g"