diff --git a/asymptote.spec b/asymptote.spec
index 79e4f13..e3d2087 100644
--- a/asymptote.spec
+++ b/asymptote.spec
@@ -64,7 +64,7 @@ for scientific text.
 rm -fv libatomic_ops-*.tar.gz gc-*.tar.gz
 
 %build
-if ! -e configure; then autoreconf -fiv; fi
+if [ ! -e configure ]; then autoreconf -fiv; fi
 %configure --with-docdir="%_docdir/%name"
 %make_build