diff --git a/.gitignore b/.gitignore
index a784f2a1fd7..84f2bfa1c6b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -56,6 +56,5 @@ tensorflow-tfjs-*.tgz
 tfjs-backend-wasm/dist
 tfjs-backend-wasm/wasm-out/*.js
 tfjs-backend-wasm/wasm-out/*.wasm
-tfjs-backend-wasm/wasm-out/*.worker.ts
 yalc.lock
 yarn-error.log
diff --git a/tfjs-backend-wasm/karma.conf.js b/tfjs-backend-wasm/karma.conf.js
index 86b2c5544a0..796311cd15c 100644
--- a/tfjs-backend-wasm/karma.conf.js
+++ b/tfjs-backend-wasm/karma.conf.js
@@ -61,8 +61,6 @@ module.exports = function(config) {
       {pattern: 'wasm-out/**/*.wasm', included: false},
       // Import the generated js library from emscripten.
       {pattern: 'wasm-out/**/*.js'},
-      // Import the generated worker file from emscripten.
-      {pattern: 'wasm-out/tfjs-backend-wasm-threaded-simd.worker.ts'},
       // Import the rest of the sources.
       {pattern: 'src/**/*.ts'},
     ],
diff --git a/tfjs-backend-wasm/src/backend_wasm.ts b/tfjs-backend-wasm/src/backend_wasm.ts
index 395a6921362..321d490e16c 100644
--- a/tfjs-backend-wasm/src/backend_wasm.ts
+++ b/tfjs-backend-wasm/src/backend_wasm.ts
@@ -418,12 +418,12 @@ export function setWasmPaths(
     wasmFileMap = prefixOrFileMap;
     const missingPaths =
         wasmBinaryNames.filter(name => wasmFileMap[name] == null);
-    if (missingPaths.length) {
-      console.warn(
-          `You provided a map of overrides for WASM binaries, but there ` +
-          `were no entries found for the following binaries: ` +
-          `${missingPaths.join(',')}. We will fall back to their ` +
-          `default locations.`);
+    if (missingPaths.length > 0) {
+      throw new Error(
+          `There were no entries found for the following binaries: ` +
+          `${missingPaths.join(',')}. Please either call setWasmPaths with a ` +
+          `map providing a path for each binary, or with a string indicating ` +
+          `the directory where all the binaries can be found.`);
     }
   }
 
diff --git a/tfjs-backend-wasm/src/index_test.ts b/tfjs-backend-wasm/src/index_test.ts
index 47d406f02c2..d009ef56025 100644
--- a/tfjs-backend-wasm/src/index_test.ts
+++ b/tfjs-backend-wasm/src/index_test.ts
@@ -111,7 +111,11 @@ describeWithFlags('wasm init', BROWSER_ENVS, () => {
   it('backend init fails when setWasmPaths is called with ' +
          'an invalid fileMap',
      async () => {
-       setWasmPaths({'tfjs-backend-wasm.wasm': 'invalid/path'});
+       setWasmPaths({
+         'tfjs-backend-wasm.wasm': 'invalid/path',
+         'tfjs-backend-wasm-simd.wasm': 'invalid/path',
+         'tfjs-backend-wasm-threaded-simd.wasm': 'invalid/path'
+       });
        let wasmPathPrefix: string;
        const realFetch = fetch;
        spyOn(self, 'fetch').and.callFake((path: string) => {
@@ -122,6 +126,16 @@ describeWithFlags('wasm init', BROWSER_ENVS, () => {
        expect(wasmPathPrefix).toBe('invalid/path');
      });
 
+  it('setWasmPaths throws error when called without specifying a path for ' +
+         'each binary',
+     async () => {
+       expect(() => {
+         setWasmPaths({
+           'tfjs-backend-wasm.wasm': '/base/wasm-out/tfjs-backend-wasm.wasm'
+         });
+       }).toThrow();
+     });
+
   it('backend init works when the path is valid and use platform fetch',
      async () => {
        const usePlatformFetch = true;
@@ -137,6 +151,30 @@ describeWithFlags('wasm init', BROWSER_ENVS, () => {
        expect(wasmPath).toBe(validPrefix + 'tfjs-backend-wasm.wasm');
      });
 
+  it('backend init works when the wasm paths overrides map is valid and ' +
+         'using platform fetch',
+     async () => {
+       const usePlatformFetch = true;
+       const validPrefix = '/base/wasm-out/';
+       setWasmPaths(
+           {
+             'tfjs-backend-wasm.wasm': '/base/wasm-out/tfjs-backend-wasm.wasm',
+             'tfjs-backend-wasm-simd.wasm':
+                 '/base/wasm-out/tfjs-backend-wasm.wasm',
+             'tfjs-backend-wasm-threaded-simd.wasm':
+                 '/base/wasm-out/tfjs-backend-wasm.wasm'
+           },
+           usePlatformFetch);
+       let wasmPath: string;
+       const realFetch = util.fetch;
+       spyOn(util, 'fetch').and.callFake((path: string) => {
+         wasmPath = path;
+         return realFetch(path);
+       });
+       expect(await tf.setBackend('wasm-test')).toBe(true);
+       expect(wasmPath).toBe(validPrefix + 'tfjs-backend-wasm.wasm');
+     });
+
   it('backend init works when the path is valid and use platform fetch',
      async () => {
        const usePlatformFetch = true;