diff --git a/src/main.rs b/src/main.rs
index 0f85a13..89a5937 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,7 +1,7 @@
 mod query_parser;
 
 use std::path::PathBuf;
-use std::str;
+use std::str::{self, FromStr};
 use std::{fs, process::exit};
 
 use anyhow::Error;
@@ -51,8 +51,15 @@ enum Args {
         /// Query within the TOML data (e.g. `dependencies.serde`, `foo[0].bar`)
         query: String,
 
-        /// String value to place at the given spot (bool, array, etc. are TODO)
-        value_str: String, // TODO more forms
+        /// Value to place at the given spot. Treated as a string if it cannot
+        /// be parsed as a non-string TOML type. Specify `--type` to enforce a
+        /// specific type.
+        value_str: String,
+
+        /// Require the value to parse as a specific type. See
+        /// `Value::type_name()` for values.
+        #[structopt(name = "type", long)]
+        required_type: Option<String>,
     },
     //
     // TODO: append/add (name TBD)
@@ -78,6 +85,8 @@ enum CliError {
     NotArray(),
     #[error("array index out of bounds")]
     ArrayIndexOob(),
+    #[error("value type does not match required type")]
+    TypeMismatch(),
 }
 
 /// An error that should cause a failure exit, but no message on stderr.
@@ -95,7 +104,8 @@ fn main() {
             path,
             query,
             value_str,
-        } => set(&path, &query, &value_str),
+            required_type,
+        } => set(&path, &query, &value_str, &required_type),
     };
     result.unwrap_or_else(|err| {
         match err.downcast::<SilentError>() {
@@ -183,7 +193,14 @@ fn print_toml_fragment(doc: &Document, tpath: &[TpathSegment]) {
     print!("{}", doc);
 }
 
-fn set(path: &PathBuf, query: &str, value_str: &str) -> Result<(), Error> {
+fn set(
+    path: &PathBuf,
+    query: &str,
+    value_str: &str,
+    required_type: &Option<String>,
+) -> Result<(), Error> {
+    let valval = parse_value(value_str, required_type)?;
+
     let tpath = parse_query_cli(query)?.0;
     let mut doc = read_parse(path)?;
 
@@ -227,7 +244,7 @@ fn set(path: &PathBuf, query: &str, value_str: &str) -> Result<(), Error> {
             }
         }
     }
-    *item = value(value_str);
+    *item = valval;
 
     // TODO actually write back
     print!("{}", doc);
@@ -254,6 +271,26 @@ fn walk_tpath<'a>(
     Some(item)
 }
 
+fn parse_value(value_str: &str, required_type: &Option<String>) -> Result<Item, Error> {
+    Ok(match required_type.as_deref() {
+        None => match Value::from_str(value_str) {
+            Ok(Value::String(_)) => value(value_str),
+            Ok(v) => value(v),
+            Err(_) => value(value_str),
+        },
+        Some("string") => value(value_str),
+        Some(type_name) => Value::from_str(value_str)
+            .map_err(|_| CliError::TypeMismatch())
+            .and_then(|v| {
+                if v.type_name() == type_name {
+                    Ok(value(v))
+                } else {
+                    Err(CliError::TypeMismatch())
+                }
+            })?,
+    })
+}
+
 // TODO Can we do newtypes more cleanly than this?
 struct JsonItem<'a>(&'a toml_edit::Item);
 
diff --git a/test/test.rs b/test/test.rs
index 2d705a1..f42c63e 100644
--- a/test/test.rs
+++ b/test/test.rs
@@ -104,42 +104,112 @@ tomltest_get_err_empty!(get_missing, ["nosuchkey"]);
 tomltest_get_err_empty!(get_missing_num, ["key[1]"]);
 
 macro_rules! tomltest_set {
-    ($name:ident, $args:expr, $expected:expr) => {
+    ($name:ident, $args:expr, $expected:literal) => {
         tomltest!($name, |mut t: TestCaseState| {
-            t.write_file(INITIAL);
+            t.write_file(&("\n".to_owned() + INITIAL + "\n"));
             t.cmd.args(["set", &t.filename()]).args($args);
-            check_eq(&$expected, &t.expect_success());
+            check_eq(&format!($expected), &t.expect_success());
         });
     };
 }
 
-const INITIAL: &str = r#"
-[x]
-y = 1
-"#;
+const INITIAL: &str = "[x]\ny = 1";
 
-#[rustfmt::skip]
-tomltest_set!(set_string_existing, ["x.y", "new"], r#"
+tomltest_set!(
+    set_auto_string_replace_existing,
+    ["x.y", "update"],
+    r#"
 [x]
-y = "new"
-"#);
+y = "update"
+"#
+);
 
-#[rustfmt::skip]
-tomltest_set!(set_string_existing_table, ["x.z", "123"], format!(
-r#"{INITIAL}z = "123"
-"#));
+tomltest_set!(
+    set_auto_string_extend_existing,
+    ["x.z", "new"],
+    r#"
+{INITIAL}
+z = "new"
+"#
+);
+
+tomltest_set!(
+    set_auto_string_new_table,
+    ["foo.bar", "baz"],
+    r#"
+{INITIAL}
 
-#[rustfmt::skip]
-tomltest_set!(set_string_new_table, ["foo.bar", "baz"], format!(
-r#"{INITIAL}
 [foo]
 bar = "baz"
-"#));
+"#
+);
 
-#[rustfmt::skip]
-tomltest_set!(set_string_toplevel, ["foo", "bar"], format!(
-r#"foo = "bar"
-{INITIAL}"#));
+tomltest_set!(
+    set_auto_string_new_toplevel,
+    ["foo", "bar"],
+    r#"foo = "bar"
+
+{INITIAL}
+"#
+);
+
+tomltest_set!(
+    set_auto_bool_replace_existing,
+    ["x.y", "true"],
+    r#"
+[x]
+y = true
+"#
+);
+
+tomltest_set!(
+    set_auto_string_array_replace_existing,
+    ["x.y", r#"["a", "b"]"#],
+    r#"
+[x]
+y = ["a", "b"]
+"#
+);
+
+tomltest_set!(
+    set_require_string_for_intlike_value,
+    ["x.y", "2", "--type", "string"],
+    r#"
+[x]
+y = "2"
+"#
+);
+
+tomltest_set!(
+    set_auto_string_with_quoted_string,
+    ["x.y", r#""update""#],
+    r#"
+[x]
+y = "\"update\""
+"#
+);
+
+macro_rules! tomltest_set_err {
+    ($name:ident, $args:expr, $pattern:expr) => {
+        tomltest!($name, |mut t: TestCaseState| {
+            t.write_file(&("\n".to_owned() + INITIAL + "\n"));
+            t.cmd.args(["set", &t.filename()]).args($args);
+            check_contains($pattern, &t.expect_error());
+        });
+    };
+}
+
+tomltest_set_err!(
+    set_require_int_got_string,
+    ["x.y", "foo", "--type", "int"],
+    "toml: value type does not match required type"
+);
+
+tomltest_set_err!(
+    set_require_bool_got_int,
+    ["x.y", "2", "--type", "boolean"],
+    "toml: value type does not match required type"
+);
 
 // TODO test `set` on string with newlines and other fun characters
 // TODO test `set` when existing value is an array, table, or array of tables