diff --git a/ir/base.def b/ir/base.def
index aaaa1f4b4c9..55672794acc 100644
--- a/ir/base.def
+++ b/ir/base.def
@@ -332,17 +332,36 @@ class Annotation {
             Vector<Expression>,
             IndexedVector<NamedExpression>> body;
 
-    inline auto &getUnparsed() { return std::get<UnparsedAnnotation>(body); }
-    inline const auto &getUnparsed() const { return std::get<UnparsedAnnotation>(body); }
-    inline auto &getExpr() { return std::get<ExpressionAnnotation>(body); }
-    inline const auto &getExpr() const { return std::get<ExpressionAnnotation>(body); }
+    inline auto &getUnparsed() {
+        BUG_CHECK(annotationKind() == Kind::Unparsed, "Annotation has been parsed already.");
+        return std::get<UnparsedAnnotation>(body);
+    }
+    inline const auto &getUnparsed() const {
+        BUG_CHECK(annotationKind() == Kind::Unparsed, "Annotation has been parsed already.");
+        return std::get<UnparsedAnnotation>(body);
+    }
+    inline auto &getExpr() {
+        BUG_CHECK(annotationKind() == Kind::Unstructured || annotationKind() == Kind::StructuredExpressionList, "Annotation does not contain an expression list.");
+        return std::get<ExpressionAnnotation>(body);
+     }
+    inline const auto &getExpr() const {
+        BUG_CHECK(annotationKind() == Kind::Unstructured || annotationKind() == Kind::StructuredExpressionList, "Annotation does not contain an expression list.");
+        return std::get<ExpressionAnnotation>(body);
+    }
     inline Expression getExpr(size_t idx) const {
+        BUG_CHECK(annotationKind() == Kind::Unstructured || annotationKind() == Kind::StructuredExpressionList, "Annotation does not contain an expression list.");
         const auto &expr = getExpr();
         BUG_CHECK(idx < expr.size(), "invalid annotation expression index");
         return expr[idx];
     }
-    inline auto &getKV() { return std::get<KVAnnotation>(body); }
-    inline const auto &getKV() const { return std::get<KVAnnotation>(body); }
+    inline auto &getKV() {
+        BUG_CHECK(annotationKind() == Kind::StructuredKVList, "Annotation does not contain a key-value list.");
+        return std::get<KVAnnotation>(body);
+    }
+    inline const auto &getKV() const {
+        BUG_CHECK(annotationKind() == Kind::StructuredKVList, "Annotation does not contain a key-value list.");
+        return std::get<KVAnnotation>(body);
+    }
 
     /// If this is true this is a structured annotation, and there are some
     /// constraints on its contents.