diff --git a/system-tests/projects/plugin-before-browser-launch-deprecation/cypress/e2e/app.cy.js b/system-tests/projects/plugin-before-browser-launch-deprecation/cypress/e2e/app.cy.js
index 7696b3805a64..6655ffce2865 100644
--- a/system-tests/projects/plugin-before-browser-launch-deprecation/cypress/e2e/app.cy.js
+++ b/system-tests/projects/plugin-before-browser-launch-deprecation/cypress/e2e/app.cy.js
@@ -8,5 +8,5 @@ it('asserts on browser args', () => {
     return
   }
 
-  cy.task('assertPsOutput')
+  cy.task('assertPsOutput', Cypress.browser.name)
 })
diff --git a/system-tests/projects/plugin-before-browser-launch-deprecation/cypress/e2e/app_spec2.js b/system-tests/projects/plugin-before-browser-launch-deprecation/cypress/e2e/app_spec2.js
index ddfbfb4f0f25..8556e56cb660 100644
--- a/system-tests/projects/plugin-before-browser-launch-deprecation/cypress/e2e/app_spec2.js
+++ b/system-tests/projects/plugin-before-browser-launch-deprecation/cypress/e2e/app_spec2.js
@@ -8,5 +8,5 @@ it('2 - asserts on browser args', () => {
     return
   }
 
-  cy.task('assertPsOutput')
+  cy.task('assertPsOutput', Cypress.browser.name)
 })
diff --git a/system-tests/projects/plugin-before-browser-launch-deprecation/plugins/index.js b/system-tests/projects/plugin-before-browser-launch-deprecation/plugins/index.js
index 8ced89f538ca..ca5138f50890 100644
--- a/system-tests/projects/plugin-before-browser-launch-deprecation/plugins/index.js
+++ b/system-tests/projects/plugin-before-browser-launch-deprecation/plugins/index.js
@@ -26,13 +26,22 @@ const getHandlersByType = (type) => {
       return {
         onBeforeBrowserLaunch (browser, launchOptions) {
           // this will emit a warning but only once
-          launchOptions = launchOptions.concat(['--foo'])
-          launchOptions.push('--foo=bar')
-          launchOptions.unshift('--load-extension=/foo/bar/baz.js')
+          // with firefox & geckodriver, you cannot pipe extraneous arguments to the browser or else the browser will fail to launch
+          if (browser.name === 'firefox') {
+            launchOptions = launchOptions.concat(['-height', `768`, '-width', '1366'])
+          } else {
+            launchOptions = launchOptions.concat(['--foo'])
+            launchOptions.push('--foo=bar')
+            launchOptions.unshift('--load-extension=/foo/bar/baz.js')
+          }
 
           return launchOptions
         },
-        onTask: { assertPsOutput: assertPsOutput(['--foo', '--foo=bar']) },
+        onTask: {
+          assertPsOutput (args) {
+            return args === 'firefox' ? assertPsOutput(['-height', '-width']) : assertPsOutput(['--foo', '--foo=bar'])
+          },
+        },
       }
 
     case 'return-new-array-without-mutation':
@@ -50,12 +59,22 @@ const getHandlersByType = (type) => {
       return {
         onBeforeBrowserLaunch (browser, launchOptions) {
           // this will NOT emit a warning
-          launchOptions.args.push('--foo')
-          launchOptions.args.unshift('--bar')
+          // with firefox & geckodriver, you cannot pipe extraneous arguments to the browser or else the browser will fail to launch
+          if (browser.name === 'firefox') {
+            launchOptions.args.push('-height', '768')
+            launchOptions.args.push('-width', '1366')
+          } else {
+            launchOptions.args.push('--foo')
+            launchOptions.args.unshift('--bar')
+          }
 
           return launchOptions
         },
-        onTask: { assertPsOutput: assertPsOutput(['--foo', '--bar']) },
+        onTask: {
+          assertPsOutput (args) {
+            return args === 'firefox' ? assertPsOutput(['-height', '-width']) : assertPsOutput(['--foo', '--bar'])
+          },
+        },
       }
 
     case 'return-undefined-mutate-array':
diff --git a/system-tests/projects/screen-size/cypress/e2e/default_size.cy.js b/system-tests/projects/screen-size/cypress/e2e/default_size.cy.js
index d9c447ad2f81..0c60218985d1 100644
--- a/system-tests/projects/screen-size/cypress/e2e/default_size.cy.js
+++ b/system-tests/projects/screen-size/cypress/e2e/default_size.cy.js
@@ -32,8 +32,7 @@ describe('windowSize', () => {
         // availHeight: top.screen.availHeight,
       }).deep.eq({
         innerWidth: 1280,
-        // NOTE: Firefox 130.0 with the default sizing is a pixel short, which we are accounting for here
-        innerHeight: Cypress.browser.name === 'firefox' ? 719 : 720,
+        innerHeight: 720,
         // screenWidth: 1280,
         // screenHeight: 720,
         // availWidth: 1280,
diff --git a/system-tests/test/firefox_spec.ts b/system-tests/test/firefox_spec.ts
index 04f8ca92f205..20595e38c197 100644
--- a/system-tests/test/firefox_spec.ts
+++ b/system-tests/test/firefox_spec.ts
@@ -48,10 +48,14 @@ describe('e2e firefox', function () {
     // snapshot: true,
   })
 
-  systemTests.it('launches maximized by default', {
+  // we only launch maximized by default headfully. Otherwise, we launch 1280x720 by default in headless.
+  // the default size of firefox headless is 1366x768 so this test will never pass headlessly
+  // @see https://github.com/mozilla/geckodriver/issues/1354#issuecomment-479456411
+  systemTests.it('launches maximized by default (headful)', {
     browser: 'firefox',
     project: 'screen-size',
     spec: 'maximized.cy.js',
+    headed: true,
     onRun: async (exec) => {
       const { stderr } = await exec({
         processEnv: {