diff --git a/pkl-cli/src/main/kotlin/org/pkl/cli/commands/EvalCommand.kt b/pkl-cli/src/main/kotlin/org/pkl/cli/commands/EvalCommand.kt
index 376fc98f..56624110 100644
--- a/pkl-cli/src/main/kotlin/org/pkl/cli/commands/EvalCommand.kt
+++ b/pkl-cli/src/main/kotlin/org/pkl/cli/commands/EvalCommand.kt
@@ -15,6 +15,7 @@
  */
 package org.pkl.cli.commands
 
+import com.github.ajalt.clikt.completion.CompletionCandidates
 import com.github.ajalt.clikt.parameters.options.default
 import com.github.ajalt.clikt.parameters.options.flag
 import com.github.ajalt.clikt.parameters.options.option
@@ -33,6 +34,7 @@ class EvalCommand : ModulesCommand(name = "eval", helpLink = helpLink) {
         names = arrayOf("-o", "--output-path"),
         metavar = "path",
         help = "File path where the output file is placed.",
+        completionCandidates = CompletionCandidates.Path,
       )
       .single()
 
@@ -59,6 +61,7 @@ class EvalCommand : ModulesCommand(name = "eval", helpLink = helpLink) {
         names = arrayOf("-m", "--multiple-file-output-path"),
         metavar = "path",
         help = "Directory where a module's multiple file output is placed.",
+        completionCandidates = CompletionCandidates.Path,
       )
       .single()
       .validate {
diff --git a/pkl-cli/src/main/kotlin/org/pkl/cli/commands/ProjectCommand.kt b/pkl-cli/src/main/kotlin/org/pkl/cli/commands/ProjectCommand.kt
index d87c6939..2fde8ee1 100644
--- a/pkl-cli/src/main/kotlin/org/pkl/cli/commands/ProjectCommand.kt
+++ b/pkl-cli/src/main/kotlin/org/pkl/cli/commands/ProjectCommand.kt
@@ -15,6 +15,7 @@
  */
 package org.pkl.cli.commands
 
+import com.github.ajalt.clikt.completion.CompletionCandidates
 import com.github.ajalt.clikt.core.Context
 import com.github.ajalt.clikt.core.NoOpCliktCommand
 import com.github.ajalt.clikt.core.subcommands
@@ -116,6 +117,7 @@ class PackageCommand : BaseCommand(name = "package", helpLink = helpLink) {
         names = arrayOf("--output-path"),
         help = "The directory to write artifacts to",
         metavar = "path",
+        completionCandidates = CompletionCandidates.Path,
       )
       .single()
       .default(".out/%{name}@%{version}")
diff --git a/pkl-cli/src/main/kotlin/org/pkl/cli/commands/TestCommand.kt b/pkl-cli/src/main/kotlin/org/pkl/cli/commands/TestCommand.kt
index fd4f300e..4fb5bc16 100644
--- a/pkl-cli/src/main/kotlin/org/pkl/cli/commands/TestCommand.kt
+++ b/pkl-cli/src/main/kotlin/org/pkl/cli/commands/TestCommand.kt
@@ -15,6 +15,7 @@
  */
 package org.pkl.cli.commands
 
+import com.github.ajalt.clikt.completion.CompletionCandidates
 import com.github.ajalt.clikt.parameters.arguments.argument
 import com.github.ajalt.clikt.parameters.arguments.convert
 import com.github.ajalt.clikt.parameters.arguments.multiple
@@ -30,7 +31,11 @@ class TestCommand : BaseCommand(name = "test", helpLink = helpLink) {
   override val helpString = "Run tests within the given module(s)"
 
   val modules: List<URI> by
-    argument(name = "modules", help = "Module paths or URIs to evaluate.")
+    argument(
+        name = "modules",
+        help = "Module paths or URIs to evaluate.",
+        completionCandidates = CompletionCandidates.Path,
+      )
       .convert { BaseOptions.parseModuleName(it) }
       .multiple()
 
diff --git a/pkl-commons-cli/src/main/kotlin/org/pkl/commons/cli/commands/BaseOptions.kt b/pkl-commons-cli/src/main/kotlin/org/pkl/commons/cli/commands/BaseOptions.kt
index 20579c15..bb1c8175 100644
--- a/pkl-commons-cli/src/main/kotlin/org/pkl/commons/cli/commands/BaseOptions.kt
+++ b/pkl-commons-cli/src/main/kotlin/org/pkl/commons/cli/commands/BaseOptions.kt
@@ -15,6 +15,7 @@
  */
 package org.pkl.commons.cli.commands
 
+import com.github.ajalt.clikt.completion.CompletionCandidates
 import com.github.ajalt.clikt.parameters.groups.OptionGroup
 import com.github.ajalt.clikt.parameters.options.*
 import com.github.ajalt.clikt.parameters.types.enum
@@ -165,6 +166,7 @@ class BaseOptions : OptionGroup() {
     option(
         names = arrayOf("-f", "--format"),
         help = "Output format to generate. <${output.joinToString()}>",
+        completionCandidates = CompletionCandidates.Fixed(output.toSet()),
       )
       .single()
 
@@ -187,9 +189,13 @@ class BaseOptions : OptionGroup() {
       .splitAll(File.pathSeparator)
 
   val settings: URI? by
-    option(names = arrayOf("--settings"), help = "Pkl settings module to use.").single().convert {
-      parseModuleName(it)
-    }
+    option(
+        names = arrayOf("--settings"),
+        help = "Pkl settings module to use.",
+        completionCandidates = CompletionCandidates.Path,
+      )
+      .single()
+      .convert { parseModuleName(it) }
 
   val timeout: Duration? by
     option(
diff --git a/pkl-commons-cli/src/main/kotlin/org/pkl/commons/cli/commands/ModulesCommand.kt b/pkl-commons-cli/src/main/kotlin/org/pkl/commons/cli/commands/ModulesCommand.kt
index 1d00baab..fff56a2a 100644
--- a/pkl-commons-cli/src/main/kotlin/org/pkl/commons/cli/commands/ModulesCommand.kt
+++ b/pkl-commons-cli/src/main/kotlin/org/pkl/commons/cli/commands/ModulesCommand.kt
@@ -15,6 +15,7 @@
  */
 package org.pkl.commons.cli.commands
 
+import com.github.ajalt.clikt.completion.CompletionCandidates
 import com.github.ajalt.clikt.parameters.arguments.argument
 import com.github.ajalt.clikt.parameters.arguments.convert
 import com.github.ajalt.clikt.parameters.arguments.multiple
@@ -24,7 +25,11 @@ import java.net.URI
 abstract class ModulesCommand(name: String, helpLink: String) :
   BaseCommand(name = name, helpLink = helpLink) {
   open val modules: List<URI> by
-    argument(name = "modules", help = "Module paths or URIs to evaluate.")
+    argument(
+        name = "modules",
+        help = "Module paths or URIs to evaluate.",
+        completionCandidates = CompletionCandidates.Path,
+      )
       .convert { BaseOptions.parseModuleName(it) }
       .multiple(required = true)