1 files changed, 9 insertions, 2 deletions

diff --git a/configure.ac b/configure.ac
index c4c759d4e..83e530750 100644
--- a/configure.ac
+++ b/configure.ac
@@ -164,8 +164,15 @@ if test "$GCC" = "yes" || test "$GCC" = "egcs"; then
         OSSH_CHECK_CFLAG_COMPILE([-Wunused-result], [-Wno-unused-result])
         OSSH_CHECK_CFLAG_COMPILE([-fno-strict-aliasing])
     if test "x$use_toolchain_hardening" = "x1"; then
-        OSSH_CHECK_CFLAG_COMPILE([-mfunction-return=thunk]) # gcc
-        OSSH_CHECK_CFLAG_COMPILE([-mindirect-branch=thunk]) # gcc
+        # Cygwin GCC 7.x allows thunking on the CLI, but produces non-working
+        # code.  Unfortunately you only notice this at link time.
+        case "$host" in
+        *-*-cygwin*) ;;
+        *)
+            OSSH_CHECK_CFLAG_COMPILE([-mfunction-return=thunk]) # gcc
+            OSSH_CHECK_CFLAG_COMPILE([-mindirect-branch=thunk]) # gcc
+            ;;
+        esac
         OSSH_CHECK_CFLAG_COMPILE([-mretpoline]) # clang
         OSSH_CHECK_LDFLAG_LINK([-Wl,-z,retpolineplt])
         OSSH_CHECK_CFLAG_COMPILE([-D_FORTIFY_SOURCE=2])