diff --git a/src/V3AstNodeDType.h b/src/V3AstNodeDType.h
index 8542bfa1f..635095644 100644
--- a/src/V3AstNodeDType.h
+++ b/src/V3AstNodeDType.h
@@ -158,7 +158,7 @@ public:
     bool widthSized() const VL_MT_SAFE { return !m_widthMin || m_widthMin == m_width; }
     bool generic() const VL_MT_SAFE { return m_generic; }
     void generic(bool flag) { m_generic = flag; }
-    std::pair<uint32_t, uint32_t> dimensions(bool includeBasic);
+    std::pair<uint32_t, uint32_t> dimensions(bool includeBasic) const;
     uint32_t arrayUnpackedElements() const;  // 1, or total multiplication of all dimensions
     static int uniqueNumInc() { return ++s_uniqueNum; }
     const char* charIQWN() const {
diff --git a/src/V3AstNodes.cpp b/src/V3AstNodes.cpp
index d046745a4..9b5c9947f 100644
--- a/src/V3AstNodes.cpp
+++ b/src/V3AstNodes.cpp
@@ -1034,11 +1034,11 @@ uint32_t AstNodeDType::arrayUnpackedElements() const {
     return entries;
 }
 
-std::pair<uint32_t, uint32_t> AstNodeDType::dimensions(bool includeBasic) {
+std::pair<uint32_t, uint32_t> AstNodeDType::dimensions(bool includeBasic) const {
     // How many array dimensions (packed,unpacked) does this Var have?
     uint32_t packed = 0;
     uint32_t unpacked = 0;
-    for (AstNodeDType* dtypep = this; dtypep;) {
+    for (const AstNodeDType* dtypep = this; dtypep;) {
         dtypep = dtypep->skipRefp();  // Skip AstRefDType/AstTypedef, or return same node
         if (const AstNodeArrayDType* const adtypep = VN_CAST(dtypep, NodeArrayDType)) {
             if (VN_IS(adtypep, PackArrayDType)) {