From 295fae0edca38a36d8031a7d3188a32396772b1b Mon Sep 17 00:00:00 2001
From: Dominick Grochowina <groho@users.noreply.github.com>
Date: Sun, 11 May 2025 08:01:13 -0400
Subject: [PATCH] Fix nullptr segfault in VerilatedVcd::emitTimeChange()
 (#5980)

---
 docs/CONTRIBUTORS           | 1 +
 include/verilated_vcd_c.cpp | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/docs/CONTRIBUTORS b/docs/CONTRIBUTORS
index 28cce9e65..28f3c1c1f 100644
--- a/docs/CONTRIBUTORS
+++ b/docs/CONTRIBUTORS
@@ -45,6 +45,7 @@ David Stanford
 David Turner
 Dercury
 Diego Roux
+Dominick Grochowina
 Don Williamson
 Drew Ranck
 Drew Taussig
diff --git a/include/verilated_vcd_c.cpp b/include/verilated_vcd_c.cpp
index 6bc7896b6..4b6588522 100644
--- a/include/verilated_vcd_c.cpp
+++ b/include/verilated_vcd_c.cpp
@@ -193,7 +193,7 @@ void VerilatedVcd::emitTimeChange(uint64_t timeui) {
     // timestamp backup and overwrite it.
     // This is faster then checking on every signal change if time needs to
     // be emitted.  Note buffer flushes may still emit a rare duplicate.
-    if (m_wrTimeEndp == m_writep) m_writep = m_wrTimeBeginp;
+    if (m_wrTimeBeginp && m_wrTimeEndp == m_writep) m_writep = m_wrTimeBeginp;
     m_wrTimeBeginp = m_writep;
     {
         printStr("#");