diff --git a/.circleci/config.yml b/.circleci/config.yml
index 8bd70f869..42c27b22c 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -54,6 +54,21 @@ jobs:
             - node_modules
       - store_artifacts:
           path: ./coverage/lcov.info
+  clash-check:
+    docker:
+      - image: maxsam4/solidity-kit
+    steps:
+      - checkout
+      - restore_cache:
+          key: dependency-cache-{{ checksum "package.json" }}
+      - run: yarn install
+      - run: node --version
+      - run: truffle version
+      - run: npm run clash-check
+      - save_cache:
+          key: dependency-cache-{{ checksum "package.json" }}
+          paths:
+            - node_modules
   docs:
     docker:
       - image: maxsam4/solidity-kit
@@ -74,6 +89,7 @@ workflows:
   commit:
     jobs:
       - coverage
+      - clash-check
   daily-builds:
     triggers:
       - schedule:
diff --git a/contracts/mocks/FunctionSigClash1.sol b/contracts/mocks/FunctionSigClash1.sol
new file mode 100644
index 000000000..51f505ade
--- /dev/null
+++ b/contracts/mocks/FunctionSigClash1.sol
@@ -0,0 +1,4 @@
+contract functionSigClash1 {
+    // function clash550254402() public {
+    // }
+}
diff --git a/contracts/mocks/FunctionSigClash2.sol b/contracts/mocks/FunctionSigClash2.sol
new file mode 100644
index 000000000..0cd0e9f9e
--- /dev/null
+++ b/contracts/mocks/FunctionSigClash2.sol
@@ -0,0 +1,4 @@
+contract functionSigClash2 {
+    // function proxyOwner() public {
+    // }
+}
diff --git a/package.json b/package.json
index a33a07af8..3adad2e2c 100644
--- a/package.json
+++ b/package.json
@@ -8,6 +8,7 @@
   },
   "scripts": {
     "test": "scripts/test.sh 2> /dev/null",
+    "clash-check": "node scripts/clashCheck.js",
     "gas": "scripts/gasUsage.sh",
     "wintest": "scripts\\wintest.cmd",
     "wincov": "scripts\\wincov.cmd",
diff --git a/scripts/clashCheck.js b/scripts/clashCheck.js
new file mode 100644
index 000000000..09f36d31c
--- /dev/null
+++ b/scripts/clashCheck.js
@@ -0,0 +1,55 @@
+const fs = require('fs');
+const exec = require('child_process').execSync;
+const chalk = require('chalk');
+const Web3 = require('web3');
+
+async function readFiles() {
+    if (fs.existsSync("./build/contracts/")) {
+        return fs.readdirSync("./build/contracts/");
+    } else {
+        console.log(chalk.yellow('Compiling contracts. This may take a while, please wait.'));
+        exec('truffle compile');
+        return fs.readdirSync("./build/contracts/");
+    }
+}
+
+async function checkClashes() {
+    console.log(chalk.green("Starting function selector clash check"));
+    let files = await readFiles();
+    let contractFunctions = new Set();
+    let functionSelectors = new Map();
+    files.forEach(item => {
+        let ABI = JSON.parse(fs.readFileSync(`./build/contracts/${item}`).toString()).abi;
+        ABI.forEach(element => {
+            if (element['type'] == 'function') {
+                let functionSig = element['name'] + '(';
+                element['inputs'].forEach(input => {
+                    functionSig = functionSig + input['type'] + ',';
+                });
+                if(functionSig[functionSig.length - 1] == ',')
+                    functionSig = functionSig.slice(0, -1) + ')';
+                else
+                    functionSig = functionSig + ')';
+                contractFunctions.add(functionSig);
+            }
+        });
+    });
+    let clashesFound = false;
+    contractFunctions.forEach(functionSig => {
+        let fnSelector = Web3.utils.sha3(functionSig).slice(0, 10);
+        if(functionSelectors.has(fnSelector)) {
+            clashesFound = true;
+            console.log(chalk.red('Function selector clash found!', functionSelectors.get(fnSelector), 'and', functionSig, 'have the same function selector:', fnSelector));
+            functionSelectors.set(fnSelector, functionSelectors.get(fnSelector) + ', ' + functionSig);
+        } else {
+            functionSelectors.set(fnSelector, functionSig);
+        }
+    });
+    if (clashesFound) {
+        console.log(chalk.yellow("The clash(es) might be in two different contracts and hence not be am Issue.\nThis script can not detect this (yet) because of proxy contracts"));
+        throw("Clash(es) found! Please fix.");
+    }  
+    console.log(chalk.green("Clash check finished. No Clashes found."));
+}
+
+checkClashes();
\ No newline at end of file