diff --git a/libc/thread/pthread_cond_destroy.c b/libc/thread/pthread_cond_destroy.c
index 0b77c88f2..c5a180e4a 100644
--- a/libc/thread/pthread_cond_destroy.c
+++ b/libc/thread/pthread_cond_destroy.c
@@ -32,7 +32,7 @@ errno_t pthread_cond_destroy(pthread_cond_t *cond) {
 
   // check if there's active waiters
 #if PTHREAD_USE_NSYNC
-  if (cond->_pshared) {
+  if (!cond->_pshared) {
     if (((nsync_cv *)cond)->waiters)
       return EINVAL;
   } else {
diff --git a/test/posix/pthread_process_shared_test.c b/test/posix/pthread_process_shared_test.c
new file mode 100644
index 000000000..449f54198
--- /dev/null
+++ b/test/posix/pthread_process_shared_test.c
@@ -0,0 +1,93 @@
+#include <pthread.h>
+#include <stdatomic.h>
+#include <stdio.h>
+#include <sys/mman.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+int main() {
+  int ws;
+  FILE *f;
+  pid_t pid;
+  pthread_condattr_t ca;
+  pthread_mutexattr_t ma;
+  struct Shared {
+    atomic_int state;
+    pthread_cond_t cond;
+    pthread_mutex_t lock;
+  } *s;
+  if (!(f = tmpfile()))
+    return 0;
+  if (ftruncate(fileno(f), 512))
+    return 1;
+  if ((s = (struct Shared *)mmap(0, 512, PROT_READ | PROT_WRITE,
+                                 MAP_SHARED | MAP_ANONYMOUS, -1, 0)) ==
+      MAP_FAILED)
+    return 2;
+  if (pthread_condattr_init(&ca))
+    return 3;
+  if (pthread_mutexattr_init(&ma))
+    return 4;
+  if (pthread_condattr_setpshared(&ca, PTHREAD_PROCESS_SHARED))
+    return 5;
+  if (pthread_mutexattr_setpshared(&ma, PTHREAD_PROCESS_SHARED))
+    return 6;
+  if (pthread_cond_init(&s->cond, &ca))
+    return 7;
+  if (pthread_mutex_init(&s->lock, &ma))
+    return 8;
+  if (pthread_mutexattr_destroy(&ma))
+    return 9;
+  if (pthread_condattr_destroy(&ca))
+    return 10;
+  if ((pid = fork()) == -1)
+    return 11;
+  if (!pid) {
+    alarm(2);
+    if (pthread_mutex_lock(&s->lock))
+      return 12;
+    s->state = 1;
+    if (pthread_cond_wait(&s->cond, &s->lock))
+      return 13;
+    if (pthread_mutex_unlock(&s->lock))
+      return 14;
+    for (;;)
+      if (s->state == 2)
+        break;
+    if (pthread_mutex_lock(&s->lock))
+      return 15;
+    if (pthread_cond_signal(&s->cond))
+      return 16;
+    if (pthread_mutex_unlock(&s->lock))
+      return 17;
+    _exit(0);
+  }
+  alarm(2);
+  for (;;)
+    if (s->state == 1)
+      break;
+  if (pthread_mutex_lock(&s->lock))
+    return 18;
+  if (pthread_cond_signal(&s->cond))
+    return 19;
+  if (pthread_mutex_unlock(&s->lock))
+    return 20;
+  if (pthread_mutex_lock(&s->lock))
+    return 21;
+  s->state = 2;
+  if (pthread_cond_wait(&s->cond, &s->lock))
+    return 22;
+  if (pthread_mutex_unlock(&s->lock))
+    return 23;
+  if (wait(&ws) != pid)
+    return 24;
+  if (!WIFEXITED(ws))
+    return 25;
+  if (WEXITSTATUS(ws))
+    return 26;
+  if (pthread_mutex_destroy(&s->lock))
+    return 27;
+  if (pthread_cond_destroy(&s->cond))
+    return 28;
+  return 0;
+}