diff --git a/cli/smartcontract/generate_test.go b/cli/smartcontract/generate_test.go
index e2a31d913..6c6a63f90 100644
--- a/cli/smartcontract/generate_test.go
+++ b/cli/smartcontract/generate_test.go
@@ -547,4 +547,7 @@ func TestCompile_GuessEventTypes(t *testing.T) {
 	t.Run("extended types mismatch", func(t *testing.T) {
 		check(t, filepath.Join("testdata", "invalid8"), "inconsistent usages of event `SomeEvent`: extended type of param #0 mismatch")
 	})
+	t.Run("named types redeclare", func(t *testing.T) {
+		check(t, filepath.Join("testdata", "invalid9"), "configured declared named type intersects with the contract's one: `invalid9.NamedStruct`")
+	})
 }
diff --git a/cli/smartcontract/testdata/invalid9/invalid.go b/cli/smartcontract/testdata/invalid9/invalid.go
new file mode 100644
index 000000000..5036bca9f
--- /dev/null
+++ b/cli/smartcontract/testdata/invalid9/invalid.go
@@ -0,0 +1,12 @@
+package invalid9
+
+import "github.com/nspcc-dev/neo-go/pkg/interop/runtime"
+
+type NamedStruct struct {
+	SomeInt int
+}
+
+func Main() NamedStruct {
+	runtime.Notify("SomeEvent", []interface{}{123})
+	return NamedStruct{SomeInt: 123}
+}
diff --git a/cli/smartcontract/testdata/invalid9/invalid.yml b/cli/smartcontract/testdata/invalid9/invalid.yml
new file mode 100644
index 000000000..40bbf66db
--- /dev/null
+++ b/cli/smartcontract/testdata/invalid9/invalid.yml
@@ -0,0 +1,16 @@
+name: Test undeclared event
+events:
+  - name: SomeEvent
+    parameters:
+      - name: p1
+        type: Array
+        extendedtype:
+          base: Array
+          name: invalid9.NamedStruct
+namedtypes:
+  invalid9.NamedStruct:
+    base: Array
+    name: invalid9.NamedStruct
+    fields:
+      - field: SomeInt
+        base: Integer
diff --git a/pkg/compiler/compiler.go b/pkg/compiler/compiler.go
index 2b90ac07e..a7826a552 100644
--- a/pkg/compiler/compiler.go
+++ b/pkg/compiler/compiler.go
@@ -340,7 +340,9 @@ func CompileAndSave(src string, o *Options) ([]byte, error) {
 			cfg.NamedTypes = di.NamedTypes
 		}
 		for name, et := range o.DeclaredNamedTypes {
-			// TODO: handle name conflict (it can happen due to invalid user input e.g.)
+			if _, ok := cfg.NamedTypes[name]; ok {
+				return nil, fmt.Errorf("configured declared named type intersects with the contract's one: `%s`", name)
+			}
 			cfg.NamedTypes[name] = et
 		}
 		for _, e := range o.ContractEvents {