diff --git a/.circleci/config.yml b/.circleci/config.yml
index a5265445..deeb4e9b 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -350,7 +350,7 @@ jobs:
 
             echo "contract C {}" > C.sol
             dist/solc.js C.sol --bin
-            [[ -f C_sol_C.bin ]]
+            [[ -f C.bin ]]
       - run:
           name: "CLI smoke test (package)"
           command: |
@@ -362,7 +362,7 @@ jobs:
 
             echo "contract C {}" > C.sol
             npx solcjs C.sol --bin
-            [[ -f C_sol_C.bin ]]
+            [[ -f C.bin ]]
 
   solidity-solcjs-ext-test:
     docker:
diff --git a/solc.ts b/solc.ts
index 10dc8ed3..e54f9e4a 100755
--- a/solc.ts
+++ b/solc.ts
@@ -44,6 +44,7 @@ program
     'When using a package manager to install libraries, use this option to specify directories where packages are installed. ' +
     'Can be used multiple times to provide multiple locations.'
   )
+  .option('--overwrite', 'If artifacts already exist on disk, overwrite them.', false)
   .option('-o, --output-dir <output-directory>', 'Output directory for the contracts.')
   .option('-p, --pretty-json', 'Pretty-print all JSON output.', false)
   .option('-v, --verbose', 'More detailed console output.', false);
@@ -224,26 +225,33 @@ if (!output) {
 
 fs.mkdirSync(destination, { recursive: true });
 
-function writeFile (file, content) {
-  file = path.join(destination, file);
+function writeFile (file, extension, content) {
+  file = path.join(destination, `${file}.${extension}`);
+
+  if (fs.existsSync(file) && !options.overwrite) {
+    throw new Error(`Refusing to overwrite existing file ${file} (use --overwrite to force).`);
+  }
+
   fs.writeFile(file, content, function (err) {
     if (err) {
-      console.error('Failed to write ' + file + ': ' + err);
+      throw new Error(`Failed to write ${file}: ${err}`);
     }
   });
 }
 
 for (const fileName in output.contracts) {
   for (const contractName in output.contracts[fileName]) {
-    let contractFileName = fileName + ':' + contractName;
-    contractFileName = contractFileName.replace(/[:./\\]/g, '_');
-
-    if (options.bin) {
-      writeFile(contractFileName + '.bin', output.contracts[fileName][contractName].evm.bytecode.object);
-    }
+    try {
+      if (options.bin) {
+        writeFile(contractName, 'bin', output.contracts[fileName][contractName].evm.bytecode.object);
+      }
 
-    if (options.abi) {
-      writeFile(contractFileName + '.abi', toFormattedJson(output.contracts[fileName][contractName].abi));
+      if (options.abi) {
+        writeFile(contractName, 'abi', toFormattedJson(output.contracts[fileName][contractName].abi));
+      }
+    } catch (err) {
+      console.error(err.message);
+      hasError = true;
     }
   }
 }
diff --git a/test/cli.ts b/test/cli.ts
index ab86e3f5..fcbdf81e 100644
--- a/test/cli.ts
+++ b/test/cli.ts
@@ -1,11 +1,21 @@
 import tape from 'tape';
 import spawn from 'tape-spawn';
+import rimraf from 'rimraf';
+import tmp from 'tmp';
+import fs from 'fs';
 import * as path from 'path';
 import solc from '../';
 
+const dist = path.resolve(__dirname, '..');
+const solcjs = path.join(dist, 'solc.js');
+
+function cleanupArtifacts () {
+  rimraf.sync(`${dist}/*{.bin,.abi}`);
+}
+
 tape('CLI', function (t) {
   t.test('--version', function (st) {
-    const spt = spawn(st, './solc.js --version');
+    const spt = spawn(st, `node ${solcjs} --version`);
     spt.stdout.match(solc.version() + '\n');
     spt.stdout.match(/^\s*[0-9]+\.[0-9]+\.[0-9]+(-[a-zA-Z0-9.]+)?\+commit\.[0-9a-f]+([a-zA-Z0-9.-]+)?\s*$/);
     spt.stderr.empty();
@@ -13,81 +23,87 @@ tape('CLI', function (t) {
   });
 
   t.test('no parameters', function (st) {
-    const spt = spawn(st, './solc.js');
+    const spt = spawn(st, `node ${solcjs}`);
     spt.stderr.match(/^Must provide a file/);
     spt.end();
   });
 
   t.test('no mode specified', function (st) {
-    const spt = spawn(st, './solc.js test/resources/fixtureSmoke.sol');
+    const spt = spawn(st, `node ${solcjs} test/resources/fixtureSmoke.sol`);
     spt.stderr.match(/^Invalid option selected/);
     spt.end();
   });
 
   t.test('--bin', function (st) {
-    const spt = spawn(st, './solc.js --bin test/resources/fixtureSmoke.sol');
+    const spt = spawn(st, `node ${solcjs} --bin test/resources/fixtureSmoke.sol`);
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('--bin --optimize', function (st) {
-    const spt = spawn(st, './solc.js --bin --optimize test/resources/fixtureSmoke.sol');
+    const spt = spawn(st, `node ${solcjs} --bin --optimize test/resources/fixtureSmoke.sol`);
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('--bin --optimize-runs 666', function (st) {
-    const spt = spawn(st, './solc.js --bin --optimize-runs 666 test/resources/fixtureSmoke.sol');
+    const spt = spawn(st, `node ${solcjs} --bin --optimize-runs 666 test/resources/fixtureSmoke.sol`);
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('--bin --optimize-runs not-a-number', function (st) {
-    const spt = spawn(st, './solc.js --bin --optimize-runs not-a-number test/resources/fixtureSmoke.sol');
+    const spt = spawn(st, `node ${solcjs} --bin --optimize-runs not-a-number test/resources/fixtureSmoke.sol`);
     spt.stderr.match(/^error: option '--optimize-runs <optimize-runs>' argument 'not-a-number' is invalid/);
     spt.end();
   });
 
   t.test('invalid file specified', function (st) {
-    const spt = spawn(st, './solc.js --bin test/fileNotFound.sol');
+    const spt = spawn(st, `node ${solcjs} --bin test/fileNotFound.sol`);
     spt.stderr.match(/^Error reading /);
     spt.end();
   });
 
   t.test('incorrect source source', function (st) {
-    const spt = spawn(st, './solc.js --bin test/resources/fixtureIncorrectSource.sol');
+    const spt = spawn(st, `node ${solcjs} --bin test/resources/fixtureIncorrectSource.sol`);
     spt.stderr.match(/SyntaxError: Invalid pragma "contract"/);
     spt.end();
   });
 
   t.test('--abi', function (st) {
-    const spt = spawn(st, './solc.js --abi test/resources/fixtureSmoke.sol');
+    const spt = spawn(st, `node ${solcjs} --abi test/resources/fixtureSmoke.sol`);
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('--bin --abi', function (st) {
-    const spt = spawn(st, './solc.js --bin --abi test/resources/fixtureSmoke.sol');
+    const spt = spawn(st, `node ${solcjs} --bin --abi test/resources/fixtureSmoke.sol`);
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('no base path', function (st) {
     const spt = spawn(
       st,
-      './solc.js --bin ' +
-        'test/resources/importA.sol ' +
-        './test/resources//importA.sol ' +
-        path.resolve('test/resources/importA.sol')
+        `node ${solcjs} --bin \
+            test/resources/importA.sol \
+            ./test/resources//importA.sol \
+            ${path.resolve('test/resources/importA.sol')}`
     );
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('relative base path', function (st) {
@@ -96,65 +112,69 @@ tape('CLI', function (t) {
     // by the import callback when it appends the base path back.
     const spt = spawn(
       st,
-      './solc.js --bin --base-path test/resources ' +
-        'test/resources/importA.sol ' +
-        './test/resources//importA.sol ' +
-        path.resolve('test/resources/importA.sol')
+      `node ${solcjs} --bin --base-path test/resources \
+            test/resources/importA.sol \
+            ./test/resources//importA.sol \
+            ${path.resolve('test/resources/importA.sol')}`
     );
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('relative non canonical base path', function (st) {
     const spt = spawn(
       st,
-      './solc.js --bin --base-path ./test/resources ' +
-        'test/resources/importA.sol ' +
-        './test/resources//importA.sol ' +
-        path.resolve('test/resources/importA.sol')
+      `node ${solcjs} --bin --base-path ./test/resources \
+            test/resources/importA.sol \
+            ./test/resources//importA.sol \
+            ${path.resolve('test/resources/importA.sol')}`
     );
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('absolute base path', function (st) {
     const spt = spawn(
       st,
-      './solc.js --bin --base-path ' + path.resolve('test/resources') + ' ' +
-        'test/resources/importA.sol ' +
-        './test/resources//importA.sol ' +
-        path.resolve('test/resources/importA.sol')
+      `node ${solcjs} --bin --base-path ${path.resolve('test/resources')} \
+            test/resources/importA.sol \
+            ./test/resources//importA.sol \
+            ${path.resolve('test/resources/importA.sol')}`
     );
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('include paths', function (st) {
     const spt = spawn(
       st,
-      './solc.js --bin ' +
-        'test/resources/importCallback/base/contractB.sol ' +
-        'test/resources/importCallback/includeA/libY.sol ' +
-        './test/resources/importCallback/includeA//libY.sol ' +
-        path.resolve('test/resources/importCallback/includeA/libY.sol') + ' ' +
-        '--base-path test/resources/importCallback/base ' +
-        '--include-path test/resources/importCallback/includeA ' +
-        '--include-path ' + path.resolve('test/resources/importCallback/includeB/')
+      `node ${solcjs} --bin \
+            test/resources/importCallback/base/contractB.sol \
+            test/resources/importCallback/includeA/libY.sol \
+            ./test/resources/importCallback/includeA//libY.sol \
+            ${path.resolve('test/resources/importCallback/includeA/libY.sol')} \
+            --base-path test/resources/importCallback/base \
+            --include-path test/resources/importCallback/includeA \
+            --include-path ${path.resolve('test/resources/importCallback/includeB/')}`
     );
     spt.stderr.empty();
     spt.succeeds();
     spt.end();
+    st.teardown(cleanupArtifacts);
   });
 
   t.test('include paths without base path', function (st) {
     const spt = spawn(
       st,
-      './solc.js --bin ' +
-        'test/resources/importCallback/contractC.sol ' +
-        '--include-path test/resources/importCallback/includeA'
+      `node ${solcjs} --bin \
+            test/resources/importCallback/contractC.sol \
+            --include-path test/resources/importCallback/includeA`
     );
     spt.stderr.match(/--include-path option requires a non-empty base path\./);
     spt.fails();
@@ -164,10 +184,10 @@ tape('CLI', function (t) {
   t.test('empty include paths', function (st) {
     const spt = spawn(
       st,
-      './solc.js --bin ' +
-        'test/resources/importCallback/contractC.sol ' +
-        '--base-path test/resources/importCallback/base ' +
-        '--include-path='
+      `node ${solcjs} --bin \
+            test/resources/importCallback/contractC.sol \
+            --base-path test/resources/importCallback/base \
+            --include-path=`
     );
     spt.stderr.match(/Empty values are not allowed in --include-path\./);
     spt.fails();
@@ -190,7 +210,7 @@ tape('CLI', function (t) {
         }
       }
     };
-    const spt = spawn(st, './solc.js --standard-json');
+    const spt = spawn(st, `node ${solcjs} --standard-json`);
     spt.stdin.setEncoding('utf-8');
     spt.stdin.write(JSON.stringify(input));
     spt.stdin.end();
@@ -219,7 +239,7 @@ tape('CLI', function (t) {
         }
       }
     };
-    const spt = spawn(st, './solc.js --standard-json --base-path test/resources');
+    const spt = spawn(st, `node ${solcjs} --standard-json --base-path test/resources`);
     spt.stdin.setEncoding('utf-8');
     spt.stdin.write(JSON.stringify(input));
     spt.stdin.end();
@@ -245,10 +265,10 @@ tape('CLI', function (t) {
     };
     const spt = spawn(
       st,
-      './solc.js --standard-json ' +
-        '--base-path test/resources/importCallback/base ' +
-        '--include-path test/resources/importCallback/includeA ' +
-        '--include-path ' + path.resolve('test/resources/importCallback/includeB/')
+      `node ${solcjs} --standard-json \
+            --base-path test/resources/importCallback/base \
+            --include-path test/resources/importCallback/includeA \
+            --include-path ${path.resolve('test/resources/importCallback/includeB/')}`
     );
     spt.stdin.setEncoding('utf-8');
     spt.stdin.write(JSON.stringify(input));
@@ -260,4 +280,25 @@ tape('CLI', function (t) {
       spt.end();
     });
   });
+
+  t.test('attempt to overwrite without --overwrite flag', function (st) {
+    const cwd = tmp.dirSync({ unsafeCleanup: true }).name;
+    // create a fake C.bin to cause name collision
+    fs.openSync(`${cwd}/C.bin`, 'w');
+
+    const spt = spawn(st, `node ${solcjs} --bin ${dist}/test/resources/fixtureSmoke.sol`, { cwd });
+    spt.stderr.match(/^Refusing to overwrite existing file C\.bin \(use --overwrite to force\)\./);
+    spt.end();
+  });
+
+  t.test('--overwrite', function (st) {
+    const cwd = tmp.dirSync({ unsafeCleanup: true }).name;
+    // create a fake C.bin to cause name collision
+    fs.openSync(`${cwd}/C.bin`, 'w');
+
+    const spt = spawn(st, `node ${solcjs} --bin ${dist}/test/resources/fixtureSmoke.sol --overwrite`, { cwd });
+    spt.stderr.empty();
+    spt.succeeds();
+    spt.end();
+  });
 });