diff --git a/src/V3Ast.cpp b/src/V3Ast.cpp
index 0a0da2598..3100e128e 100644
--- a/src/V3Ast.cpp
+++ b/src/V3Ast.cpp
@@ -1067,7 +1067,9 @@ void AstNode::dumpTreeFile(const string& filename, bool append, bool doDump) {
     editCountSetLast();
 }
 
-void AstNode::v3errorEndFatal(std::ostringstream& str) const { v3errorEnd(str); assert(0); }
+void AstNode::v3errorEndFatal(std::ostringstream& str) const {
+    v3errorEnd(str); assert(0); VL_UNREACHABLE
+}
 
 void AstNode::v3errorEnd(std::ostringstream& str) const {
     if (!m_fileline) {
diff --git a/src/V3FileLine.h b/src/V3FileLine.h
index 3af449b3d..e52dc5b4c 100644
--- a/src/V3FileLine.h
+++ b/src/V3FileLine.h
@@ -172,6 +172,8 @@ private:
 };
 std::ostream& operator<<(std::ostream& os, FileLine* fileline);
 
-inline void FileLine::v3errorEndFatal(std::ostringstream& str) { v3errorEnd(str); assert(0); }
+inline void FileLine::v3errorEndFatal(std::ostringstream& str) {
+    v3errorEnd(str); assert(0); VL_UNREACHABLE
+}
 
-#endif // Guard
+#endif  // Guard
diff --git a/src/V3Graph.cpp b/src/V3Graph.cpp
index 0bd00dde8..0322285c0 100644
--- a/src/V3Graph.cpp
+++ b/src/V3Graph.cpp
@@ -147,7 +147,7 @@ void V3GraphVertex::v3errorEnd(std::ostringstream& str) const {
     }
 }
 void V3GraphVertex::v3errorEndFatal(std::ostringstream& str) const {
-    v3errorEnd(str); assert(0);
+    v3errorEnd(str); assert(0); VL_UNREACHABLE
 }
 
 std::ostream& operator<<(std::ostream& os, V3GraphVertex* vertexp) {