diff --git a/Changelog.md b/Changelog.md
index 248165bbc..cf6498a16 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -4,6 +4,8 @@ Features:
  * Inline Assembly: Issue warning for using jump labels (already existed for jump instructions).
 
 Bugfixes:
+ * Type Checker: Suggest the experimental ABI encoder if using ``struct``s as function parameters
+   (instead of an internal compiler error).
 
 ### 0.4.19 (2017-11-30)
 
diff --git a/libsolidity/analysis/TypeChecker.cpp b/libsolidity/analysis/TypeChecker.cpp
index 96160a751..a578ad0f7 100644
--- a/libsolidity/analysis/TypeChecker.cpp
+++ b/libsolidity/analysis/TypeChecker.cpp
@@ -570,6 +570,17 @@ bool TypeChecker::visit(FunctionDefinition const& _function)
 			m_errorReporter.typeError(var->location(), "Type is required to live outside storage.");
 		if (_function.visibility() >= FunctionDefinition::Visibility::Public && !(type(*var)->interfaceType(isLibraryFunction)))
 			m_errorReporter.fatalTypeError(var->location(), "Internal or recursive type is not allowed for public or external functions.");
+		if (
+			_function.visibility() > FunctionDefinition::Visibility::Internal &&
+			type(*var)->category() == Type::Category::Struct &&
+			!type(*var)->dataStoredIn(DataLocation::Storage) &&
+			!_function.sourceUnit().annotation().experimentalFeatures.count(ExperimentalFeature::ABIEncoderV2)
+		)
+			m_errorReporter.typeError(
+				var->location(),
+				"Structs are only supported in the new experimental ABI encoder. "
+				"Use \"pragma experimental ABIEncoderV2;\" to enable the feature."
+			);
 
 		var->accept(*this);
 	}
diff --git a/test/libsolidity/SMTChecker.cpp b/test/libsolidity/SMTChecker.cpp
index 38d026010..3a65aa433 100644
--- a/test/libsolidity/SMTChecker.cpp
+++ b/test/libsolidity/SMTChecker.cpp
@@ -94,6 +94,7 @@ BOOST_AUTO_TEST_CASE(warn_on_typecast)
 BOOST_AUTO_TEST_CASE(warn_on_struct)
 {
 	string text = R"(
+		pragma experimental ABIEncoderV2;
 		contract C {
 			struct A { uint a; uint b; }
 			function f() public pure returns (A) {
diff --git a/test/libsolidity/SolidityABIJSON.cpp b/test/libsolidity/SolidityABIJSON.cpp
index 339627300..26bfb6d08 100644
--- a/test/libsolidity/SolidityABIJSON.cpp
+++ b/test/libsolidity/SolidityABIJSON.cpp
@@ -942,6 +942,7 @@ BOOST_AUTO_TEST_CASE(function_type)
 BOOST_AUTO_TEST_CASE(return_structs)
 {
 	char const* text = R"(
+		pragma experimental ABIEncoderV2;
 		contract C {
 			struct S { uint a; T[] sub; }
 			struct T { uint[2] x; }
@@ -991,6 +992,7 @@ BOOST_AUTO_TEST_CASE(return_structs)
 BOOST_AUTO_TEST_CASE(return_structs_with_contracts)
 {
 	char const* text = R"(
+		pragma experimental ABIEncoderV2;
 		contract C {
 			struct S { C[] x; C y; }
 			function f() returns (S s, C c) {
@@ -1090,6 +1092,7 @@ BOOST_AUTO_TEST_CASE(event_structs)
 BOOST_AUTO_TEST_CASE(structs_in_libraries)
 {
 	char const* text = R"(
+		pragma experimental ABIEncoderV2;
 		library L {
 			struct S { uint a; T[] sub; bytes b; }
 			struct T { uint[2] x; }
diff --git a/test/libsolidity/SolidityNameAndTypeResolution.cpp b/test/libsolidity/SolidityNameAndTypeResolution.cpp
index 97d359e8e..39dba0dea 100644
--- a/test/libsolidity/SolidityNameAndTypeResolution.cpp
+++ b/test/libsolidity/SolidityNameAndTypeResolution.cpp
@@ -602,6 +602,7 @@ BOOST_AUTO_TEST_CASE(enum_external_type)
 BOOST_AUTO_TEST_CASE(external_structs)
 {
 	char const* text = R"(
+		pragma experimental ABIEncoderV2;
 		contract Test {
 			enum ActionChoices { GoLeft, GoRight, GoStraight, Sit }
 			struct Empty {}
@@ -629,6 +630,7 @@ BOOST_AUTO_TEST_CASE(external_structs)
 BOOST_AUTO_TEST_CASE(external_structs_in_libraries)
 {
 	char const* text = R"(
+		pragma experimental ABIEncoderV2;
 		library Test {
 			enum ActionChoices { GoLeft, GoRight, GoStraight, Sit }
 			struct Empty {}
@@ -3511,6 +3513,7 @@ BOOST_AUTO_TEST_CASE(using_for_not_used)
 BOOST_AUTO_TEST_CASE(library_memory_struct)
 {
 	char const* text = R"(
+		pragma experimental ABIEncoderV2;
 		library c {
 			struct S { uint x; }
 			function f() public returns (S ) {}
@@ -5696,6 +5699,7 @@ BOOST_AUTO_TEST_CASE(constructible_internal_constructor)
 BOOST_AUTO_TEST_CASE(return_structs)
 {
 	char const* text = R"(
+		pragma experimental ABIEncoderV2;
 		contract C {
 			struct S { uint a; T[] sub; }
 			struct T { uint[] x; }