diff --git a/sigchainlib/sigchain.cc b/sigchainlib/sigchain.cc
index b4bd68b..e61fcd8 100644
--- a/sigchainlib/sigchain.cc
+++ b/sigchainlib/sigchain.cc
@@ -169,7 +169,8 @@
   // action but don't pass it on to the kernel.
   // Note that we check that the signal number is in range here.  An out of range signal
   // number should behave exactly as the libc sigaction.
-  if (signal > 0 && signal < _NSIG && user_sigactions[signal].IsClaimed()) {
+  if (signal > 0 && signal < _NSIG && user_sigactions[signal].IsClaimed() &&
+      (new_action == nullptr || new_action->sa_handler != SIG_DFL)) {
     struct sigaction saved_action = user_sigactions[signal].GetAction();
     if (new_action != NULL) {
       user_sigactions[signal].SetAction(*new_action, false);
@@ -210,7 +211,7 @@
   // action but don't pass it on to the kernel.
   // Note that we check that the signal number is in range here.  An out of range signal
   // number should behave exactly as the libc sigaction.
-  if (signal > 0 && signal < _NSIG && user_sigactions[signal].IsClaimed()) {
+  if (signal > 0 && signal < _NSIG && user_sigactions[signal].IsClaimed() && handler != SIG_DFL) {
     oldhandler = reinterpret_cast<sighandler_t>(user_sigactions[signal].GetAction().sa_handler);
     user_sigactions[signal].SetAction(sa, true);
     return oldhandler;