diff --git a/util/update_headers.sh b/util/update_headers.sh
index 2d93646..4ba1b9f 100755
--- a/util/update_headers.sh
+++ b/util/update_headers.sh
@@ -11,17 +11,17 @@
 then
 	LINUX_ROOT="$1"
 else
-	LINUX_ROOT=/lib/modules/$(uname -r)/source
+	LINUX_ROOT="/lib/modules/$(uname -r)/source"
 fi
 
-if [ ! -d $LINUX_ROOT/include/uapi/linux ]
+if [ ! -d "$LINUX_ROOT/include/uapi/linux" ]
 then
 	echo "$LINUX_ROOT does not seem to be valid Linux source tree."
 	echo "usage: $0 [path-to-Linux-source-tree]"
 	exit 1
 fi
 
-cp $LINUX_ROOT/include/uapi/linux/kvm.h include/linux
+cp -- "$LINUX_ROOT/include/uapi/linux/kvm.h" include/linux
 
 for arch in arm arm64 mips powerpc x86
 do
@@ -30,6 +30,6 @@
 		arm64) KVMTOOL_PATH=arm/aarch64 ;;
 		*) KVMTOOL_PATH=$arch ;;
 	esac
-	cp $LINUX_ROOT/arch/$arch/include/uapi/asm/kvm.h \
-		$KVMTOOL_PATH/include/asm
+	cp -- "$LINUX_ROOT/arch/$arch/include/uapi/asm/kvm.h" \
+		"$KVMTOOL_PATH/include/asm"
 done