diff --git a/linker.js b/linker.js
index 6116aab3..b4f169ab 100644
--- a/linker.js
+++ b/linker.js
@@ -1,3 +1,4 @@
+var assert = require('assert');
 var keccak256 = require('js-sha3').keccak256;
 
 function libraryHashPlaceholder (input) {
@@ -5,6 +6,8 @@ function libraryHashPlaceholder (input) {
 }
 
 var linkBytecode = function (bytecode, libraries) {
+  assert(typeof bytecode === 'string');
+  assert(typeof libraries === 'object');
   // NOTE: for backwards compatibility support old compiler which didn't use file names
   var librariesComplete = {};
   for (var libraryName in libraries) {
@@ -52,6 +55,7 @@ var linkBytecode = function (bytecode, libraries) {
 };
 
 var findLinkReferences = function (bytecode) {
+  assert(typeof bytecode === 'string');
   // find 40 bytes in the pattern of __...<36 digits>...__
   // e.g. __Lib.sol:L_____________________________
   var linkReferences = {};
diff --git a/test/compiler.js b/test/compiler.js
index 5b3dd33c..880d1352 100644
--- a/test/compiler.js
+++ b/test/compiler.js
@@ -55,9 +55,12 @@ function runTests (solc, versionText) {
         error = output.errors[error];
         if (error.type === errorType) {
           if (message) {
-            return error.message.match(message) !== null;
+            if (error.message.match(message) !== null) {
+              return true;
+            }
+          } else {
+            return true;
           }
-          return true;
         }
       }
     }
@@ -421,7 +424,40 @@ function runTests (solc, versionText) {
         st.end();
       });
 
-      t.test('compiling standard JSON', function (st) {
+      t.test('compiling standard JSON (single file)', function (st) {
+        var input = {
+          'language': 'Solidity',
+          'settings': {
+            'outputSelection': {
+              '*': {
+                '*': [ 'evm.bytecode', 'evm.gasEstimates' ]
+              }
+            }
+          },
+          'sources': {
+            'c.sol': {
+              'content': 'contract C { function g() public { } function h() internal {} }'
+            }
+          }
+        };
+
+        var output = JSON.parse(solc.compile(JSON.stringify(input)));
+        st.ok(expectNoError(output));
+        var C = getBytecodeStandard(output, 'c.sol', 'C');
+        st.ok(typeof C === 'string');
+        st.ok(C.length > 0);
+        var CGas = getGasEstimate(output, 'c.sol', 'C');
+        st.ok(typeof CGas === 'object');
+        st.ok(typeof CGas['creation'] === 'object');
+        st.ok(typeof CGas['creation']['codeDepositCost'] === 'string');
+        st.ok(typeof CGas['external'] === 'object');
+        st.ok(typeof CGas['external']['g()'] === 'string');
+        st.ok(typeof CGas['internal'] === 'object');
+        st.ok(typeof CGas['internal']['h()'] === 'string');
+        st.end();
+      });
+
+      t.test('compiling standard JSON (multiple files)', function (st) {
         // <0.1.6 doesn't have this
         if (!solc.features.multipleInputs) {
           st.skip('Not supported by solc');
@@ -468,6 +504,40 @@ function runTests (solc, versionText) {
         st.end();
       });
 
+      t.test('compiling standard JSON (abstract contract)', function (st) {
+        // <0.1.6 doesn't have this
+        if (!solc.features.multipleInputs) {
+          st.skip('Not supported by solc');
+          st.end();
+          return;
+        }
+
+        var isVersion6 = semver.gt(solc.semver(), '0.5.99');
+
+        var input = {
+          'language': 'Solidity',
+          'settings': {
+            'outputSelection': {
+              '*': {
+                '*': [ 'evm.bytecode', 'evm.gasEstimates' ]
+              }
+            }
+          },
+          'sources': {
+            'c.sol': {
+              'content': (isVersion6 ? 'abstract ' : '') + 'contract C { function f() public; }'
+            }
+          }
+        };
+
+        var output = JSON.parse(solc.compile(JSON.stringify(input)));
+        st.ok(expectNoError(output));
+        var C = getBytecodeStandard(output, 'c.sol', 'C');
+        st.ok(typeof C === 'string');
+        st.ok(C.length === 0);
+        st.end();
+      });
+
       t.test('compiling standard JSON (with imports)', function (st) {
         // <0.2.1 doesn't have this
         if (!solc.features.importCallback) {
@@ -606,6 +676,35 @@ function runTests (solc, versionText) {
         st.end();
       });
 
+      t.test('compiling standard JSON (with warning >=0.4.0)', function (st) {
+        // In 0.4.0 "pragma solidity" was added. Not including it is a warning.
+        if (semver.lt(solc.semver(), '0.4.0')) {
+          st.skip('Not supported by solc');
+          st.end();
+          return;
+        }
+
+        var input = {
+          'language': 'Solidity',
+          'settings': {
+            'outputSelection': {
+              '*': {
+                '*': [ 'evm.bytecode' ]
+              }
+            }
+          },
+          'sources': {
+            'c.sol': {
+              'content': 'contract C { function f() public { } }'
+            }
+          }
+        };
+
+        var output = JSON.parse(solc.compile(JSON.stringify(input)));
+        st.ok(expectError(output, 'Warning', 'Source file does not specify required compiler version!'));
+        st.end();
+      });
+
       t.test('compiling standard JSON (using libraries) (using lowlevel API)', function (st) {
         // 0.4.0 has a bug with libraries
         if (semver.eq(solc.semver(), '0.4.0')) {
diff --git a/translate.js b/translate.js
index 43e051ad..17dbc704 100644
--- a/translate.js
+++ b/translate.js
@@ -110,15 +110,15 @@ function translateJsonCompilerOutput (output, libraries) {
       'evm': {
         'legacyAssembly': contractInput['assembly'],
         'bytecode': {
-          'object': linker.linkBytecode(contractInput['bytecode'], libraries),
+          'object': contractInput['bytecode'] && linker.linkBytecode(contractInput['bytecode'], libraries || {}),
           'opcodes': contractInput['opcodes'],
           'sourceMap': contractInput['srcmap'],
-          'linkReferences': linker.findLinkReferences(contractInput['bytecode'])
+          'linkReferences': contractInput['bytecode'] && linker.findLinkReferences(contractInput['bytecode'])
         },
         'deployedBytecode': {
-          'object': linker.linkBytecode(contractInput['runtimeBytecode'], libraries),
+          'object': contractInput['runtimeBytecode'] && linker.linkBytecode(contractInput['runtimeBytecode'], libraries || {}),
           'sourceMap': contractInput['srcmapRuntime'],
-          'linkReferences': linker.findLinkReferences(contractInput['runtimeBytecode'])
+          'linkReferences': contractInput['runtimeBytecode'] && linker.findLinkReferences(contractInput['runtimeBytecode'])
         },
         'methodIdentifiers': contractInput['functionHashes'],
         'gasEstimates': translatedGasEstimates