diff --git a/debuggerd/libdebuggerd/tombstone.cpp b/debuggerd/libdebuggerd/tombstone.cpp
index ee64c3d..534d7be 100644
--- a/debuggerd/libdebuggerd/tombstone.cpp
+++ b/debuggerd/libdebuggerd/tombstone.cpp
@@ -36,6 +36,7 @@
 #include <string>
 
 #include <android-base/file.h>
+#include <android-base/logging.h>
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
@@ -417,6 +418,8 @@
   }
 
   if (primary_thread) {
+    // The main thread must have a valid siginfo.
+    CHECK(thread_info.siginfo != nullptr);
     dump_probable_cause(log, unwinder, process_info, thread_info);
 
     dump_abort_message(log, unwinder->GetProcessMemory().get(), process_info.abort_msg_address);
diff --git a/debuggerd/libdebuggerd/tombstone_proto.cpp b/debuggerd/libdebuggerd/tombstone_proto.cpp
index e8e2ae2..6c380a1 100644
--- a/debuggerd/libdebuggerd/tombstone_proto.cpp
+++ b/debuggerd/libdebuggerd/tombstone_proto.cpp
@@ -40,6 +40,7 @@
 #include <async_safe/log.h>
 
 #include <android-base/file.h>
+#include <android-base/logging.h>
 #include <android-base/properties.h>
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
@@ -616,6 +617,8 @@
   result.set_tid(main_thread.tid);
   result.set_uid(main_thread.uid);
   result.set_selinux_label(main_thread.selinux_label);
+  // The main thread must have a valid siginfo.
+  CHECK(main_thread.siginfo != nullptr);
 
   struct sysinfo si;
   sysinfo(&si);