diff --git a/build.sh b/build.sh
index d84b67ee4b..0c548634ef 100755
--- a/build.sh
+++ b/build.sh
@@ -155,7 +155,7 @@ done
 
 target="qemu-system-i386"
 if test ! -z "$debug"; then
-    build_cflags='-DXEMU_DEBUG_BUILD=1'
+    build_cflags='-O0 -g3 -DXEMU_DEBUG_BUILD=1'
     opts="--enable-debug --enable-trace-backends=log"
 fi