diff --git a/nsprpub/pr/include/md/_pth.h b/nsprpub/pr/include/md/_pth.h
index 214fb9f98d2..c1c40893e49 100644
--- a/nsprpub/pr/include/md/_pth.h
+++ b/nsprpub/pr/include/md/_pth.h
@@ -54,14 +54,22 @@
  * Mutex and condition attributes are not supported.  The attr
  * argument to pthread_mutex_init() and pthread_cond_init() must
  * be passed as NULL.
+ *
+ * The memset calls in PTHREAD_MUTEX_INIT and PTHREAD_COND_INIT
+ * are to work around BSDI's using a single bit to indicate a mutex
+ * or condition variable is initialized.  This entire BSDI section
+ * will go away when BSDI releases updated threads libraries for
+ * BSD/OS 3.1 and 4.0.
  */
 #define PTHREAD_MUTEXATTR_INIT(x)     0
 #define PTHREAD_MUTEXATTR_DESTROY(x)  /* */
-#define PTHREAD_MUTEX_INIT(m, a)      pthread_mutex_init(&(m), NULL)
-#define PTHREAD_MUTEX_IS_LOCKED(m) (EBUSY == pthread_mutex_trylock(&(m)))
+#define PTHREAD_MUTEX_INIT(m, a)      (memset(&(m), 0, sizeof(m)), \
+                                      pthread_mutex_init(&(m), NULL))
+#define PTHREAD_MUTEX_IS_LOCKED(m)    (EBUSY == pthread_mutex_trylock(&(m)))
 #define PTHREAD_CONDATTR_INIT(x)      0
 #define PTHREAD_CONDATTR_DESTROY(x)   /* */
-#define PTHREAD_COND_INIT(m, a)       pthread_cond_init(&(m), NULL)
+#define PTHREAD_COND_INIT(m, a)       (memset(&(m), 0, sizeof(m)), \
+                                      pthread_cond_init(&(m), NULL))
 #else
 #define PTHREAD_MUTEXATTR_INIT        pthread_mutexattr_init
 #define PTHREAD_MUTEXATTR_DESTROY     pthread_mutexattr_destroy