diff --git a/security/manager/ssl/tests/unit/test_cert_dbKey.js b/security/manager/ssl/tests/unit/test_cert_dbKey.js
index f04e56a1d0b9..ca47a4997976 100644
--- a/security/manager/ssl/tests/unit/test_cert_dbKey.js
+++ b/security/manager/ssl/tests/unit/test_cert_dbKey.js
@@ -53,14 +53,8 @@ function encodeCommonNameAsBytes(commonName) {
 }
 
 function testInvalidDBKey(certDB, dbKey) {
-  let exceptionCaught = false;
-  try {
-    let cert = certDB.findCertByDBKey(dbKey);
-  } catch(e) {
-    do_print(e);
-    exceptionCaught = true;
-  }
-  ok(exceptionCaught, "should have thrown and caught an exception");
+  throws(() => certDB.findCertByDBKey(dbKey), /NS_ERROR_ILLEGAL_INPUT/,
+         `findCertByDBKey(${dbKey}) should raise NS_ERROR_ILLEGAL_INPUT`);
 }
 
 function testDBKeyForNonexistentCert(certDB, dbKey) {
diff --git a/security/manager/ssl/tests/unit/test_constructX509FromBase64.js b/security/manager/ssl/tests/unit/test_constructX509FromBase64.js
index e565c6cb99f7..a7b722a41184 100644
--- a/security/manager/ssl/tests/unit/test_constructX509FromBase64.js
+++ b/security/manager/ssl/tests/unit/test_constructX509FromBase64.js
@@ -35,26 +35,22 @@ function testGood(data) {
 }
 
 function testBad(data) {
-  try {
-    let cert = certDB.constructX509FromBase64(data.input);
-    ok(false, `Should have gotten an exception for "${data.input}"`);
-  } catch (e) {
-    equal(e.result, data.result,
-          "Actual and expected exception result should match");
-  }
+  throws(() => certDB.constructX509FromBase64(data.input), data.result,
+         `Should get "${data.result}" for "${data.input}"`);
 }
 
 function run_test() {
   const badCases = [
     // Wrong type or too short
-    { input: null, result: Cr.NS_ERROR_ILLEGAL_VALUE },
-    { input: "", result: Cr.NS_ERROR_ILLEGAL_VALUE },
-    { input: "=", result: Cr.NS_ERROR_ILLEGAL_VALUE },
-    { input: "==", result: Cr.NS_ERROR_ILLEGAL_VALUE },
+    { input: null, result: /NS_ERROR_ILLEGAL_VALUE/ },
+    { input: "", result: /NS_ERROR_ILLEGAL_VALUE/ },
+    { input: "=", result: /NS_ERROR_ILLEGAL_VALUE/ },
+    { input: "==", result: /NS_ERROR_ILLEGAL_VALUE/ },
     // Not base64
-    { input: "forty-four dead stone lions", result: Cr.NS_ERROR_ILLEGAL_VALUE },
+    { input: "forty-four dead stone lions", result: /NS_ERROR_ILLEGAL_VALUE/ },
     // Not a cert
-    { input: "Zm9ydHktZm91ciBkZWFkIHN0b25lIGxpb25z", result: Cr.NS_ERROR_FAILURE }
+    { input: "Zm9ydHktZm91ciBkZWFkIHN0b25lIGxpb25z",
+      result: /NS_ERROR_FAILURE/ },
   ];
 
   // Real certs with all three padding levels
diff --git a/security/manager/ssl/tests/unit/test_logoutAndTeardown.js b/security/manager/ssl/tests/unit/test_logoutAndTeardown.js
index 853d3e2854be..2bf8855fe128 100644
--- a/security/manager/ssl/tests/unit/test_logoutAndTeardown.js
+++ b/security/manager/ssl/tests/unit/test_logoutAndTeardown.js
@@ -16,16 +16,10 @@ function connect_and_teardown() {
 
   let reader = {
     onInputStreamReady: function(stream) {
-      try {
-        stream.available();
-        Assert.ok(false, "stream.available() should have thrown");
-      }
-      catch (e) {
-        Assert.equal(e.result, Components.results.NS_ERROR_FAILURE,
-                     "stream should be in an error state");
-        Assert.ok(tearDown, "this should be as a result of logoutAndTeardown");
-        run_next_test();
-      }
+      throws(() => stream.available(), /NS_ERROR_FAILURE/,
+             "stream should be in an error state");
+      ok(tearDown, "A tear down attempt should have occurred");
+      run_next_test();
     }
   };
 
diff --git a/security/manager/ssl/tests/unit/test_pinning_dynamic.js b/security/manager/ssl/tests/unit/test_pinning_dynamic.js
index 8adcd0057553..4b8e819265b3 100644
--- a/security/manager/ssl/tests/unit/test_pinning_dynamic.js
+++ b/security/manager/ssl/tests/unit/test_pinning_dynamic.js
@@ -149,12 +149,10 @@ function checkStateRead(aSubject, aTopic, aData) {
   checkDefaultSiteHPKPStatus();
 
   // failure to insert new pin entry leaves previous pin behavior
-  try {
+  throws(() => {
     gSSService.setKeyPins("a.pinning2.example.com", true, 1000, 1,
                           ["not a hash"]);
-    ok(false, "Attempting to set an invalid pin should have failed");
-  } catch(e) {
-  }
+  }, /NS_ERROR_ILLEGAL_VALUE/, "Attempting to set an invalid pin should fail");
   checkFail(certFromFile('cn-a.pinning2.example.com-badca'), "a.pinning2.example.com");
   checkOK(certFromFile('cn-a.pinning2.example.com-pinningroot'), "a.pinning2.example.com");
   checkOK(certFromFile('cn-x.a.pinning2.example.com-badca'), "x.a.pinning2.example.com");
@@ -170,12 +168,11 @@ function checkStateRead(aSubject, aTopic, aData) {
   checkDefaultSiteHPKPStatus();
 
   // Incorrect size results in failure
-  try {
+  throws(() => {
     gSSService.setKeyPins("a.pinning2.example.com", true, 1000, 2,
                           ["not a hash"]);
-    ok(false, "Attempting to set a pin with an incorrect size should have failed");
-  } catch(e) {
-  }
+  }, /NS_ERROR_XPC_NOT_ENOUGH_ELEMENTS_IN_ARRAY/,
+     "Attempting to set a pin with an incorrect size should fail");
 
   // Ensure built-in pins work as expected
   ok(!gSSService.isSecureHost(Ci.nsISiteSecurityService.HEADER_HPKP,
diff --git a/security/manager/ssl/tests/unit/test_pinning_header_parsing.js b/security/manager/ssl/tests/unit/test_pinning_header_parsing.js
index 9a5941203058..9ab3b636add2 100644
--- a/security/manager/ssl/tests/unit/test_pinning_header_parsing.js
+++ b/security/manager/ssl/tests/unit/test_pinning_header_parsing.js
@@ -25,13 +25,10 @@ function checkFailParseInvalidPin(pinValue) {
   let sslStatus = new FakeSSLStatus(
                         certFromFile('cn-a.pinning2.example.com-pinningroot'));
   let uri = Services.io.newURI("https://a.pinning2.example.com", null, null);
-  try {
+  throws(() => {
     gSSService.processHeader(Ci.nsISiteSecurityService.HEADER_HPKP, uri,
                              pinValue, sslStatus, 0);
-    ok(false, "Invalid pin should have been rejected");
-  } catch (e) {
-    ok(true, "Invalid pin should be rejected");
-  }
+  }, /NS_ERROR_FAILURE/, `Invalid pin "${pinValue}" should be rejected`);
 }
 
 function checkPassValidPin(pinValue, settingPin) {
diff --git a/security/manager/ssl/tests/unit/test_pkcs11_safe_mode.js b/security/manager/ssl/tests/unit/test_pkcs11_safe_mode.js
index e3ac01509f36..8264c4214c88 100644
--- a/security/manager/ssl/tests/unit/test_pkcs11_safe_mode.js
+++ b/security/manager/ssl/tests/unit/test_pkcs11_safe_mode.js
@@ -46,12 +46,6 @@ function run_test() {
   libraryFile.append("pkcs11testmodule");
   libraryFile.append(libraryName);
   ok(libraryFile.exists(), "The pkcs11testmodule file should exist");
-  let exceptionCaught = false;
-  try {
-    pkcs11.addModule("PKCS11 Test Module", libraryFile.path, 0, 0);
-    ok(false, "addModule should have thrown an exception");
-  } catch (e) {
-    exceptionCaught = true;
-  }
-  ok(exceptionCaught, "addModule should have thrown an exception");
+  throws(() => pkcs11.addModule("PKCS11 Test Module", libraryFile.path, 0, 0),
+         /NS_ERROR_FAILURE/, "addModule should throw when in safe mode");
 }
diff --git a/security/manager/ssl/tests/unit/test_sts_fqdn.js b/security/manager/ssl/tests/unit/test_sts_fqdn.js
index be49318f2e35..c2c3eb2bd16d 100644
--- a/security/manager/ssl/tests/unit/test_sts_fqdn.js
+++ b/security/manager/ssl/tests/unit/test_sts_fqdn.js
@@ -44,10 +44,7 @@ function run_test() {
   // gracefully.
   uri = Services.io.newURI("https://../foo", null, null);
   equal(uri.host, "..");
-  try {
+  throws(() => {
     SSService.isSecureURI(Ci.nsISiteSecurityService.HEADER_HSTS, uri, 0);
-    ok(false); // this shouldn't run
-  } catch (e) {
-    equal(e.result, Cr.NS_ERROR_UNEXPECTED);
-  }
+  }, /NS_ERROR_UNEXPECTED/, "Malformed URI should be rejected");
 }