diff --git a/caching/cache_check.cc b/caching/cache_check.cc
index 2cbd0e4..b660e01 100644
--- a/caching/cache_check.cc
+++ b/caching/cache_check.cc
@@ -87,11 +87,35 @@ namespace {
 		using reporter_base::get_error;
 	};
 
-	class mapping_reporter : public reporter_base {
+	class mapping_reporter : public mapping_array_damage::damage_visitor, reporter_base {
 	public:
 		mapping_reporter(nested_output &o)
 		: reporter_base(o) {
 		}
+
+		virtual void visit(mapping_array_damage::missing_mappings const &d) {
+			out() << "missing mappings:" << end_message();
+			{
+				nested_output::nest _ = push();
+				out() << d.get_desc() << end_message();
+			}
+
+			mplus_error(FATAL);
+		}
+
+		virtual void visit(mapping_array_damage::invalid_mapping const &d) {
+			out() << "invalid mapping:" << end_message();
+			{
+				nested_output::nest _ = push();
+				out() << d.get_desc()
+				      << " [cblock = " << d.cblock_
+				      << ", oblock = " << d.m_.oblock_
+				      << ", flags = " << d.m_.flags_
+				      << "]" << end_message();
+			}
+
+			mplus_error(FATAL);
+		}
 	};
 
 	class hint_reporter : public reporter_base {
diff --git a/caching/mapping_array.cc b/caching/mapping_array.cc
index 1477431..d2a7e48 100644
--- a/caching/mapping_array.cc
+++ b/caching/mapping_array.cc
@@ -28,12 +28,10 @@ mapping_traits::pack(value_type const &value, disk_type &disk)
 
 //----------------------------------------------------------------
 
-missing_mappings::missing_mappings(run<uint32_t> const &keys,
-				   std::string const &desc)
-	: keys_(keys),
-	  desc_(desc)
+missing_mappings::missing_mappings(std::string const &desc, run<uint32_t> const &keys)
+	: damage(desc),
+	  keys_(keys)
 {
-
 }
 
 void
@@ -42,6 +40,20 @@ missing_mappings::visit(damage_visitor &v) const
 	v.visit(*this);
 }
 
+invalid_mapping::invalid_mapping(std::string const &desc,
+				 block_address cblock, mapping const &m)
+	: damage(desc),
+	  cblock_(cblock),
+	  m_(m)
+{
+}
+
+void
+invalid_mapping::visit(damage_visitor &v) const
+{
+	v.visit(*this);
+}
+
 namespace {
 	struct no_op_visitor {
 		virtual void visit(uint32_t index,
@@ -56,7 +68,7 @@ namespace {
 		}
 
 		virtual void visit(array_detail::damage const &d) {
-			v_.visit(missing_mappings(d.lost_keys_, d.desc_));
+			v_.visit(missing_mappings(d.desc_, d.lost_keys_));
 		}
 
 	private:
diff --git a/caching/mapping_array.h b/caching/mapping_array.h
index fde0c28..29f9390 100644
--- a/caching/mapping_array.h
+++ b/caching/mapping_array.h
@@ -28,17 +28,36 @@ namespace caching {
 	namespace mapping_array_damage {
 		class damage_visitor;
 
-		struct damage {
+		class damage {
+		public:
+			damage(std::string const &desc)
+				: desc_(desc) {
+			}
+
 			virtual ~damage() {}
 			virtual void visit(damage_visitor &v) const = 0;
+
+			std::string get_desc() const {
+				return desc_;
+			}
+
+		private:
+			std::string desc_;
 		};
 
 		struct missing_mappings : public damage {
-			missing_mappings(run<uint32_t> const &keys, std::string const &desc);
+			missing_mappings(std::string const &desc, run<uint32_t> const &keys);
 			virtual void visit(damage_visitor &v) const;
 
 			run<uint32_t> keys_;
-			std::string desc_;
+		};
+
+		struct invalid_mapping : public damage {
+			invalid_mapping(std::string const &desc, block_address cblock, mapping const &m);
+			virtual void visit(damage_visitor &v) const;
+
+			block_address cblock_;
+			mapping m_;
 		};
 
 		class damage_visitor {
@@ -50,6 +69,7 @@ namespace caching {
 			}
 
 			virtual void visit(missing_mappings const &d) = 0;
+			virtual void visit(invalid_mapping const &d) = 0;
 		};
 	}