s/NULL/nullptr
diff --git a/src/core/lib/support/sync_posix.cc b/src/core/lib/support/sync_posix.cc
index 62d800b..d306d43 100644
--- a/src/core/lib/support/sync_posix.cc
+++ b/src/core/lib/support/sync_posix.cc
@@ -33,7 +33,7 @@
gpr_atm gpr_counter_atm_add = 0;
#endif
-void gpr_mu_init(gpr_mu* mu) { GPR_ASSERT(pthread_mutex_init(mu, NULL) == 0); }
+void gpr_mu_init(gpr_mu* mu) { GPR_ASSERT(pthread_mutex_init(mu, nullptr) == 0); }
void gpr_mu_destroy(gpr_mu* mu) { GPR_ASSERT(pthread_mutex_destroy(mu) == 0); }
@@ -63,7 +63,7 @@
/*----------------------------------------*/
-void gpr_cv_init(gpr_cv* cv) { GPR_ASSERT(pthread_cond_init(cv, NULL) == 0); }
+void gpr_cv_init(gpr_cv* cv) { GPR_ASSERT(pthread_cond_init(cv, nullptr) == 0); }
void gpr_cv_destroy(gpr_cv* cv) { GPR_ASSERT(pthread_cond_destroy(cv) == 0); }