diff --git a/src/V3DfgPeephole.cpp b/src/V3DfgPeephole.cpp
index a392d9547..993050db0 100644
--- a/src/V3DfgPeephole.cpp
+++ b/src/V3DfgPeephole.cpp
@@ -233,6 +233,9 @@ class V3DfgPeephole final : public DfgVisitor {
     Vertex* make(FileLine* flp, const DfgDataType& dtype, Operands... operands) {
         // Find or create an equivalent vertex
         Vertex* const vtxp = m_cache.getOrCreate<Vertex, Operands...>(flp, dtype, operands...);
+        // Sanity check
+        UASSERT_OBJ(vtxp->dtype() == dtype, vtxp, "Vertex dtype mismatch");
+        if (VL_UNLIKELY(v3Global.opt.debugCheck())) vtxp->typeCheck(m_dfg);
         // Add to work list
         addToWorkList(vtxp);
         // Return new node