diff --git a/crypto/thread_pthread.c b/crypto/thread_pthread.c
index 59c4b8d..68aaab5 100644
--- a/crypto/thread_pthread.c
+++ b/crypto/thread_pthread.c
@@ -17,6 +17,7 @@
 #if !defined(OPENSSL_WINDOWS) && !defined(OPENSSL_NO_THREADS)
 
 #include <pthread.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -74,7 +75,11 @@
 }
 
 void CRYPTO_once(CRYPTO_once_t *once, void (*init)(void)) {
-  pthread_once(once, init);
+  if (pthread_once(once, init) != 0) {
+    fprintf(stderr,
+            "pthread_once failed. Did you link against a threading library?\n");
+    abort();
+  }
 }
 
 static pthread_mutex_t g_destructors_lock = PTHREAD_MUTEX_INITIALIZER;