diff --git a/cli/src/lib.rs b/cli/src/lib.rs
index 1cd2ea0eab..c7efdbc1a5 100644
--- a/cli/src/lib.rs
+++ b/cli/src/lib.rs
@@ -94,7 +94,7 @@ pub fn build_app<'a>() -> App<'a> {
                 .arg(Arg::with_name(DIRECTORY_OR_FILES)
                     .index(1)
                     .multiple(true)
-                    .required(true)
+                    .required(false)
                     .help("The directory or files to build documentation for")
 
                 )
diff --git a/cli/src/main.rs b/cli/src/main.rs
index fccf700c96..c4d659a5be 100644
--- a/cli/src/main.rs
+++ b/cli/src/main.rs
@@ -9,6 +9,7 @@ use target_lexicon::Triple;
 
 #[cfg(feature = "llvm")]
 use roc_cli::build;
+use std::ffi::{OsStr, OsString};
 
 #[cfg(not(feature = "llvm"))]
 fn build(_target: &Triple, _matches: &clap::ArgMatches, _config: BuildConfig) -> io::Result<i32> {
@@ -68,19 +69,34 @@ fn main() -> io::Result<()> {
             Ok(0)
         }
         Some(CMD_DOCS) => {
-            let values = matches
+            let maybe_values = matches
                 .subcommand_matches(CMD_DOCS)
                 .unwrap()
-                .values_of_os(DIRECTORY_OR_FILES)
-                .unwrap();
+                .values_of_os(DIRECTORY_OR_FILES);
+
+            let mut values: Vec<OsString> = Vec::new();
+
+            match maybe_values {
+                None => {
+                    let mut os_string_values: Vec<OsString> = Vec::new();
+                    read_all_roc_files(&OsStr::new("./").to_os_string(), &mut os_string_values)?;
+                    for os_string in os_string_values {
+                        values.push(os_string);
+                    }
+                }
+                Some(os_values) => {
+                    for os_str in os_values {
+                        values.push(os_str.to_os_string());
+                    }
+                }
+            }
 
             let mut roc_files = Vec::new();
 
             // Populate roc_files
             for os_str in values {
-                let metadata = fs::metadata(os_str)?;
-
-                roc_files_recursive(os_str, metadata.file_type(), &mut roc_files)?;
+                let metadata = fs::metadata(os_str.clone())?;
+                roc_files_recursive(os_str.as_os_str(), metadata.file_type(), &mut roc_files)?;
             }
 
             docs(roc_files);
@@ -93,6 +109,26 @@ fn main() -> io::Result<()> {
     std::process::exit(exit_code);
 }
 
+fn read_all_roc_files(
+    dir: &OsString,
+    mut roc_file_paths: &mut Vec<OsString>,
+) -> Result<(), std::io::Error> {
+    let entries = fs::read_dir(dir)?;
+
+    for entry in entries {
+        let path = entry?.path();
+
+        if path.is_dir() {
+            read_all_roc_files(&path.into_os_string(), &mut roc_file_paths)?;
+        } else if path.extension().and_then(OsStr::to_str) == Some("roc") {
+            let file_path = path.into_os_string();
+            roc_file_paths.push(file_path);
+        }
+    }
+
+    Ok(())
+}
+
 fn roc_files_recursive<P: AsRef<Path>>(
     path: P,
     file_type: FileType,