diff --git a/src/iso19111/crs.cpp b/src/iso19111/crs.cpp
index 983ee1f9d8..0cd2f604b9 100644
--- a/src/iso19111/crs.cpp
+++ b/src/iso19111/crs.cpp
@@ -3706,6 +3706,10 @@ bool VerticalCRS::_isEquivalentTo(
     const util::IComparable *other, util::IComparable::Criterion criterion,
     const io::DatabaseContextPtr &dbContext) const {
     auto otherVertCRS = dynamic_cast<const VerticalCRS *>(other);
+    if (otherVertCRS == nullptr ||
+        !util::isOfExactType<VerticalCRS>(*otherVertCRS)) {
+        return false;
+    }
     // TODO test geoidModel and velocityModel
     return otherVertCRS != nullptr &&
            SingleCRS::baseIsEquivalentTo(other, criterion, dbContext);
diff --git a/test/unit/test_crs.cpp b/test/unit/test_crs.cpp
index e16ea308ad..cdccddd03f 100644
--- a/test/unit/test_crs.cpp
+++ b/test/unit/test_crs.cpp
@@ -5962,6 +5962,19 @@ TEST(crs, parametricCRS_WKT1) {
 
 // ---------------------------------------------------------------------------
 
+TEST(crs, derivedVerticalCRS_basic) {
+
+    auto crs = createDerivedVerticalCRS();
+    EXPECT_TRUE(crs->isEquivalentTo(crs.get()));
+    EXPECT_TRUE(crs->shallowClone()->isEquivalentTo(crs.get()));
+    EXPECT_TRUE(!crs->isEquivalentTo(createUnrelatedObject().get()));
+
+    EXPECT_FALSE(crs->isEquivalentTo(crs->baseCRS().get()));
+    EXPECT_FALSE(crs->baseCRS()->isEquivalentTo(crs.get()));
+}
+
+// ---------------------------------------------------------------------------
+
 TEST(crs, DerivedVerticalCRS_WKT2) {
 
     auto expected = "VERTCRS[\"Derived vertCRS\",\n"
@@ -5976,10 +5989,6 @@ TEST(crs, DerivedVerticalCRS_WKT2) {
                     "                ID[\"EPSG\",9001]]]]";
 
     auto crs = createDerivedVerticalCRS();
-    EXPECT_TRUE(crs->isEquivalentTo(crs.get()));
-    EXPECT_TRUE(crs->shallowClone()->isEquivalentTo(crs.get()));
-    EXPECT_TRUE(!crs->isEquivalentTo(createUnrelatedObject().get()));
-
     EXPECT_EQ(crs->exportToWKT(
                   WKTFormatter::create(WKTFormatter::Convention::WKT2).get()),
               expected);