diff --git a/preinst-swig.in b/preinst-swig.in
index 4cead1d88..ac00602bb 100755
--- a/preinst-swig.in
+++ b/preinst-swig.in
@@ -3,7 +3,7 @@
 # Convenience script for running SWIG before it is installed.
 # Intended for ad-hoc usage and not by the test-suite or examples.
 
-builddir=`dirname $0`
-SWIG_LIB=@SWIG_LIB_PREINST@
+builddir=`dirname "$0"`
+SWIG_LIB='@SWIG_LIB_PREINST@'
 export SWIG_LIB
 exec "$builddir/swig" "$@"