diff --git a/src/cli/index.ts b/src/cli/index.ts
index b86a083..2d770c4 100755
--- a/src/cli/index.ts
+++ b/src/cli/index.ts
@@ -94,14 +94,14 @@ program
     const start = performance.now()
     const results: TestResult[] = []
     const cwd = process.cwd()
-    const portFrom = opts.portFrom ? parseInt(opts.portFrom, 10) : undefined
-    if (portFrom !== undefined && Number.isNaN(portFrom)) {
+    const portFrom = parseInt(opts.portFrom, 10)
+    if (Number.isNaN(portFrom)) {
       console.error("--port-from must be an integer")
       process.exit(1)
     }
     let nextPort = portFrom
 
-    const runOne = async (filePath: string, port: number | undefined) => {
+    const runOne = async (filePath: string, port: number) => {
       const content = await readFile(filePath, "utf-8")
       const parsed = parse(relative(cwd, filePath), content)
 
@@ -125,7 +125,7 @@ program
         }
       }
       Object.assign(envVars, setupEnvVars, userEnvVars)
-      if (port !== undefined && !("PORT" in userEnvVars) && !("PORT" in setupEnvVars)) {
+      if (!("PORT" in userEnvVars) && !("PORT" in setupEnvVars)) {
         envVars["PORT"] = String(port)
       }
       const merged: ShoutFile = { ...parsed, commands: [...setupCommands, ...parsed.commands] }
@@ -203,7 +203,7 @@ program
     }
 
     if (opts.parallel) {
-      const all = await Promise.all(files.map(f => runOne(f, nextPort !== undefined ? nextPort++ : undefined)))
+      const all = await Promise.all(files.map(f => runOne(f, nextPort++)))
       for (const r of all) {
         printDots(r)
         results.push(r)
@@ -211,7 +211,7 @@ program
       process.stdout.write("\n")
     } else {
       for (const filePath of files) {
-        const r = await runOne(filePath, nextPort !== undefined ? nextPort++ : undefined)
+        const r = await runOne(filePath, nextPort++)
         printDots(r)
         results.push(r)
       }