diff --git a/libc/bionic/pthread_exit.cpp b/libc/bionic/pthread_exit.cpp
index 1de85f5..ceda931 100644
--- a/libc/bionic/pthread_exit.cpp
+++ b/libc/bionic/pthread_exit.cpp
@@ -87,7 +87,7 @@
     sigaltstack(&ss, NULL);
 
     // Free it.
-    munmap(thread->alternate_signal_stack, SIGSTKSZ);
+    munmap(thread->alternate_signal_stack, SIGNAL_STACK_SIZE);
     thread->alternate_signal_stack = NULL;
   }