diff --git a/libsolidity/ast/AST.h b/libsolidity/ast/AST.h
index 15327c655..b409c84cd 100644
--- a/libsolidity/ast/AST.h
+++ b/libsolidity/ast/AST.h
@@ -504,6 +504,7 @@ public:
 	std::vector<FunctionDefinition const*> definedFunctions() const { return filteredNodes<FunctionDefinition>(m_subNodes); }
 	std::vector<EventDefinition const*> events() const { return filteredNodes<EventDefinition>(m_subNodes); }
 	std::vector<EventDefinition const*> const& interfaceEvents() const;
+	std::vector<ErrorDefinition const*> errors() const { return filteredNodes<ErrorDefinition>(m_subNodes); }
 	bool isInterface() const { return m_contractKind == ContractKind::Interface; }
 	bool isLibrary() const { return m_contractKind == ContractKind::Library; }
 
diff --git a/libsolidity/interface/ABI.cpp b/libsolidity/interface/ABI.cpp
index 70dbc1b3a..5c2fb3416 100644
--- a/libsolidity/interface/ABI.cpp
+++ b/libsolidity/interface/ABI.cpp
@@ -121,6 +121,26 @@ Json::Value ABI::generate(ContractDefinition const& _contractDef)
 		abi.emplace(std::move(event));
 	}
 
+	// TODO should use "used errors" once implemented,
+	// but should also include all errors defined in the contract.
+	for (ErrorDefinition const* error: _contractDef.errors())
+	{
+		Json::Value event;
+		event["type"] = "error";
+		event["name"] = error->name();
+		Json::Value params(Json::arrayValue);
+		for (auto const& p: error->parameters())
+		{
+			Type const* type = p->annotation().type->interfaceType(false);
+			solAssert(type, "");
+			Json::Value input;
+			auto param = formatType(p->name(), *type, *p->annotation().type, false);
+			params.append(std::move(param));
+		}
+		event["inputs"] = std::move(params);
+		abi.emplace(std::move(event));
+	}
+
 	Json::Value abiJson{Json::arrayValue};
 	for (auto& f: abi)
 		abiJson.append(std::move(f));
diff --git a/test/libsolidity/ABIJson/errors.sol b/test/libsolidity/ABIJson/errors.sol
new file mode 100644
index 000000000..7c227b20d
--- /dev/null
+++ b/test/libsolidity/ABIJson/errors.sol
@@ -0,0 +1,88 @@
+error FreeError();
+contract X {
+    error E(uint);
+    error E2(uint a, uint b);
+    error E4(uint a, bytes[][] c);
+    struct S { uint x; }
+    error E5(S t);
+    function f() public pure {
+        revert(FreeError());
+    }
+}
+// ----
+//     :X
+// [
+//   {
+//     "inputs":
+//     [
+//       {
+//         "internalType": "uint256",
+//         "name": "",
+//         "type": "uint256"
+//       }
+//     ],
+//     "name": "E",
+//     "type": "error"
+//   },
+//   {
+//     "inputs":
+//     [
+//       {
+//         "internalType": "uint256",
+//         "name": "a",
+//         "type": "uint256"
+//       },
+//       {
+//         "internalType": "uint256",
+//         "name": "b",
+//         "type": "uint256"
+//       }
+//     ],
+//     "name": "E2",
+//     "type": "error"
+//   },
+//   {
+//     "inputs":
+//     [
+//       {
+//         "internalType": "uint256",
+//         "name": "a",
+//         "type": "uint256"
+//       },
+//       {
+//         "internalType": "bytes[][]",
+//         "name": "c",
+//         "type": "bytes[][]"
+//       }
+//     ],
+//     "name": "E4",
+//     "type": "error"
+//   },
+//   {
+//     "inputs":
+//     [
+//       {
+//         "components":
+//         [
+//           {
+//             "internalType": "uint256",
+//             "name": "x",
+//             "type": "uint256"
+//           }
+//         ],
+//         "internalType": "struct X.S",
+//         "name": "t",
+//         "type": "tuple"
+//       }
+//     ],
+//     "name": "E5",
+//     "type": "error"
+//   },
+//   {
+//     "inputs": [],
+//     "name": "f",
+//     "outputs": [],
+//     "stateMutability": "pure",
+//     "type": "function"
+//   }
+// ]