diff --git a/mozilla/old-configure.in b/mozilla/old-configure.in
index 924a185..b683375 100644
--- a/mozilla/old-configure.in
+++ b/mozilla/old-configure.in
@@ -500,7 +500,7 @@ CFLAGS="$CFLAGS $HARDENING_CFLAGS"
 CPPFLAGS="$CPPFLAGS $HARDENING_CFLAGS"
 CXXFLAGS="$CXXFLAGS $HARDENING_CFLAGS"
 
-if test "$GNU_CC" -o test -n "${CLANG_CC}${CLANG_CL}"; then
+if test "$GNU_CC" || test -n "${CLANG_CC}${CLANG_CL}"; then
    CFLAGS="$CFLAGS -D_FORTIFY_SOURCE=2"
    CPPFLAGS="$CPPFLAGS -D_FORTIFY_SOURCE=2"
    CXXFLAGS="$CXXFLAGS -D_FORTIFY_SOURCE=2"