diff --git a/Cargo.lock b/Cargo.lock
index 47de1af..8942fb1 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -47,6 +47,22 @@ version = "1.0.86"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b3d1d046238990b9cf5bcde22a3fb3584ee5cf65fb2765f454ed428c7a0063da"
 
+[[package]]
+name = "assert_cmd"
+version = "2.0.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc1835b7f27878de8525dc71410b5a31cdcc5f230aed5ba5df968e09c201b23d"
+dependencies = [
+ "anstyle",
+ "bstr",
+ "doc-comment",
+ "libc",
+ "predicates",
+ "predicates-core",
+ "predicates-tree",
+ "wait-timeout",
+]
+
 [[package]]
 name = "async-stream"
 version = "0.3.5"
@@ -105,6 +121,17 @@ version = "2.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "ed570934406eb16438a4e976b1b4500774099c13b8cb96eec99f620f05090ddf"
 
+[[package]]
+name = "bstr"
+version = "1.10.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "40723b8fb387abc38f4f4a37c09073622e41dd12327033091ef8950659e6dc0c"
+dependencies = [
+ "memchr",
+ "regex-automata",
+ "serde",
+]
+
 [[package]]
 name = "bumpalo"
 version = "3.14.0"
@@ -278,6 +305,18 @@ version = "0.1.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "56254986775e3233ffa9c4d7d3faaf6d36a2c09d30b20687e9f88bc8bafc16c8"
 
+[[package]]
+name = "difflib"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6184e33543162437515c2e2b48714794e37845ec9851711914eec9d308f6ebe8"
+
+[[package]]
+name = "doc-comment"
+version = "0.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fea41bba32d969b513997752735605054bc0dfa92b4c56bf1189f2e174be7a10"
+
 [[package]]
 name = "either"
 version = "1.10.0"
@@ -294,6 +333,12 @@ dependencies = [
  "windows-sys 0.52.0",
 ]
 
+[[package]]
+name = "fastrand"
+version = "2.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e8c02a5121d4ea3eb16a80748c74f5549a5665e4c21333c6098f283870fbdea6"
+
 [[package]]
 name = "fnv"
 version = "1.0.7"
@@ -604,9 +649,9 @@ dependencies = [
 
 [[package]]
 name = "once_cell"
-version = "1.18.0"
+version = "1.19.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dd8b5dd2ae5ed71462c540258bedcb51965123ad7e7ccf4b9a8cafaa4a63576d"
+checksum = "3fdb12b2476b595f9358c5161aa467c2438859caa136dec86c26fdd2efe17b92"
 
 [[package]]
 name = "owo-colors"
@@ -653,6 +698,33 @@ version = "0.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "439ee305def115ba05938db6eb1644ff94165c5ab5e9420d1c1bcedbba909391"
 
+[[package]]
+name = "predicates"
+version = "3.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7e9086cc7640c29a356d1a29fd134380bee9d8f79a17410aa76e7ad295f42c97"
+dependencies = [
+ "anstyle",
+ "difflib",
+ "predicates-core",
+]
+
+[[package]]
+name = "predicates-core"
+version = "1.0.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ae8177bee8e75d6846599c6b9ff679ed51e882816914eec639944d7c9aa11931"
+
+[[package]]
+name = "predicates-tree"
+version = "1.0.11"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "41b740d195ed3166cd147c8047ec98db0e22ec019eb8eeb76d343b795304fb13"
+dependencies = [
+ "predicates-core",
+ "termtree",
+]
+
 [[package]]
 name = "pretty_assertions"
 version = "1.4.0"
@@ -860,10 +932,12 @@ checksum = "b7c388c1b5e93756d0c740965c41e8822f866621d41acbdf6336a6a168f8840c"
 name = "spicy-format"
 version = "0.12.0"
 dependencies = [
+ "assert_cmd",
  "clap",
  "miette",
  "pretty_assertions",
  "rayon",
+ "tempfile",
  "thiserror",
  "topiary-core",
  "topiary-tree-sitter-facade",
@@ -922,6 +996,19 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "tempfile"
+version = "3.12.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "04cbcdd0c794ebb0d4cf35e88edd2f7d2c4c3e9a5a6dab322839b321c6a87a64"
+dependencies = [
+ "cfg-if",
+ "fastrand",
+ "once_cell",
+ "rustix",
+ "windows-sys 0.59.0",
+]
+
 [[package]]
 name = "terminal_size"
 version = "0.3.0"
@@ -932,6 +1019,12 @@ dependencies = [
  "windows-sys 0.48.0",
 ]
 
+[[package]]
+name = "termtree"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3369f5ac52d5eb6ab48c6b4ffdc8efbcad6b89c765749064ba298f2c68a16a76"
+
 [[package]]
 name = "textwrap"
 version = "0.16.0"
@@ -1230,6 +1323,15 @@ version = "0.9.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 
+[[package]]
+name = "wait-timeout"
+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9f200f5b12eb75f8c1ed65abd4b2db8a6e1b138a20de009dacee265a2498f3f6"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "walkdir"
 version = "2.5.0"
@@ -1362,7 +1464,16 @@ version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "282be5f36a8ce781fad8c8ae18fa3f9beff57ec1b52cb3de0789201425d9a33d"
 dependencies = [
- "windows-targets 0.52.0",
+ "windows-targets 0.52.6",
+]
+
+[[package]]
+name = "windows-sys"
+version = "0.59.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1e38bc4d79ed67fd075bcc251a1c39b32a1776bbe92e5bef1f0bf1f8c531853b"
+dependencies = [
+ "windows-targets 0.52.6",
 ]
 
 [[package]]
@@ -1382,17 +1493,18 @@ dependencies = [
 
 [[package]]
 name = "windows-targets"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8a18201040b24831fbb9e4eb208f8892e1f50a37feb53cc7ff887feb8f50e7cd"
+checksum = "9b724f72796e036ab90c1021d4780d4d3d648aca59e491e6b98e725b84e99973"
 dependencies = [
- "windows_aarch64_gnullvm 0.52.0",
- "windows_aarch64_msvc 0.52.0",
- "windows_i686_gnu 0.52.0",
- "windows_i686_msvc 0.52.0",
- "windows_x86_64_gnu 0.52.0",
- "windows_x86_64_gnullvm 0.52.0",
- "windows_x86_64_msvc 0.52.0",
+ "windows_aarch64_gnullvm 0.52.6",
+ "windows_aarch64_msvc 0.52.6",
+ "windows_i686_gnu 0.52.6",
+ "windows_i686_gnullvm",
+ "windows_i686_msvc 0.52.6",
+ "windows_x86_64_gnu 0.52.6",
+ "windows_x86_64_gnullvm 0.52.6",
+ "windows_x86_64_msvc 0.52.6",
 ]
 
 [[package]]
@@ -1403,9 +1515,9 @@ checksum = "2b38e32f0abccf9987a4e3079dfb67dcd799fb61361e53e2882c3cbaf0d905d8"
 
 [[package]]
 name = "windows_aarch64_gnullvm"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cb7764e35d4db8a7921e09562a0304bf2f93e0a51bfccee0bd0bb0b666b015ea"
+checksum = "32a4622180e7a0ec044bb555404c800bc9fd9ec262ec147edd5989ccd0c02cd3"
 
 [[package]]
 name = "windows_aarch64_msvc"
@@ -1415,9 +1527,9 @@ checksum = "dc35310971f3b2dbbf3f0690a219f40e2d9afcf64f9ab7cc1be722937c26b4bc"
 
 [[package]]
 name = "windows_aarch64_msvc"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bbaa0368d4f1d2aaefc55b6fcfee13f41544ddf36801e793edbbfd7d7df075ef"
+checksum = "09ec2a7bb152e2252b53fa7803150007879548bc709c039df7627cabbd05d469"
 
 [[package]]
 name = "windows_i686_gnu"
@@ -1427,9 +1539,15 @@ checksum = "a75915e7def60c94dcef72200b9a8e58e5091744960da64ec734a6c6e9b3743e"
 
 [[package]]
 name = "windows_i686_gnu"
-version = "0.52.0"
+version = "0.52.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8e9b5ad5ab802e97eb8e295ac6720e509ee4c243f69d781394014ebfe8bbfa0b"
+
+[[package]]
+name = "windows_i686_gnullvm"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a28637cb1fa3560a16915793afb20081aba2c92ee8af57b4d5f28e4b3e7df313"
+checksum = "0eee52d38c090b3caa76c563b86c3a4bd71ef1a819287c19d586d7334ae8ed66"
 
 [[package]]
 name = "windows_i686_msvc"
@@ -1439,9 +1557,9 @@ checksum = "8f55c233f70c4b27f66c523580f78f1004e8b5a8b659e05a4eb49d4166cca406"
 
 [[package]]
 name = "windows_i686_msvc"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ffe5e8e31046ce6230cc7215707b816e339ff4d4d67c65dffa206fd0f7aa7b9a"
+checksum = "240948bc05c5e7c6dabba28bf89d89ffce3e303022809e73deaefe4f6ec56c66"
 
 [[package]]
 name = "windows_x86_64_gnu"
@@ -1451,9 +1569,9 @@ checksum = "53d40abd2583d23e4718fddf1ebec84dbff8381c07cae67ff7768bbf19c6718e"
 
 [[package]]
 name = "windows_x86_64_gnu"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3d6fa32db2bc4a2f5abeacf2b69f7992cd09dca97498da74a151a3132c26befd"
+checksum = "147a5c80aabfbf0c7d901cb5895d1de30ef2907eb21fbbab29ca94c5b08b1a78"
 
 [[package]]
 name = "windows_x86_64_gnullvm"
@@ -1463,9 +1581,9 @@ checksum = "0b7b52767868a23d5bab768e390dc5f5c55825b6d30b86c844ff2dc7414044cc"
 
 [[package]]
 name = "windows_x86_64_gnullvm"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1a657e1e9d3f514745a572a6846d3c7aa7dbe1658c056ed9c3344c4109a6949e"
+checksum = "24d5b23dc417412679681396f2b49f3de8c1473deb516bd34410872eff51ed0d"
 
 [[package]]
 name = "windows_x86_64_msvc"
@@ -1475,9 +1593,9 @@ checksum = "ed94fce61571a4006852b7389a063ab983c02eb1bb37b47f8272ce92d06d9538"
 
 [[package]]
 name = "windows_x86_64_msvc"
-version = "0.52.0"
+version = "0.52.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "dff9641d1cd4be8d1a070daf9e3773c5f67e78b4d9d42263020c057706765c04"
+checksum = "589f6da84c646204747d1270a2a5661ea66ed1cced2631d546fdfb155959f9ec"
 
 [[package]]
 name = "yansi"
diff --git a/Cargo.toml b/Cargo.toml
index 051441c..cfb28f4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,7 +18,9 @@ miette = { version = "7.2.0", default-features = false, features = ["derive", "f
 rayon = "1.10.0"
 
 [dev-dependencies]
+assert_cmd = { version = "2.0.16", default-features = false }
 pretty_assertions = "1.4.0"
+tempfile = { version = "3.12.0", default-features = false }
 walkdir = "2.5.0"
 
 [build-dependencies]
diff --git a/src/lib.rs b/src/lib.rs
index 90303aa..a9b8fdf 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -185,7 +185,7 @@ mod test {
                     let file_name = format!(
                         "{}.expected",
                         path.file_name()
-                            .expect(&format!(
+                            .unwrap_or_else(|| panic!(
                                 "cannot get filename component of {}",
                                 path.display()
                             ))
@@ -198,10 +198,9 @@ mod test {
                     o.join(file_name)
                 };
 
-                let formatted = format(&input, false, false).expect(&format!(
-                    "cannot format source file {}",
-                    t.path().to_string_lossy()
-                ));
+                let formatted = format(&input, false, false).unwrap_or_else(|_| {
+                    panic!("cannot format source file {}", t.path().to_string_lossy())
+                });
 
                 if !update_baseline {
                     let expected = std::fs::read_to_string(output).expect("cannot read baseline");
diff --git a/src/main.rs b/src/main.rs
index a7f0ff8..f029b90 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -58,7 +58,10 @@ fn main() -> Result<()> {
             .read_to_string(&mut buf)
             .map_err(Error::Io)
             .wrap_err("while reading input from stdin")?;
-        println!("{}", format(&buf, "<stdin>")?);
+
+        // When printing the result do not insert extra newlines.
+        let formatted = format(&buf, "<stdin>")?;
+        print!("{formatted}");
     } else {
         let failed = args
             .input_files
@@ -95,7 +98,8 @@ fn main() -> Result<()> {
                         return Some(input_file);
                     }
                 } else {
-                    println!("{formatted}");
+                    // When printing the result do not insert extra newlines.
+                    print!("{formatted}");
                 }
 
                 None
diff --git a/tests/cli.rs b/tests/cli.rs
new file mode 100644
index 0000000..f85aab1
--- /dev/null
+++ b/tests/cli.rs
@@ -0,0 +1,40 @@
+use std::{
+    io::{Read, Write},
+    process::{Command, Stdio},
+};
+
+use assert_cmd::cargo::CommandCargoExt;
+use tempfile::NamedTempFile;
+
+type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;
+
+#[test]
+fn trailing_newline_stdin() -> Result<()> {
+    let mut cmd = Command::cargo_bin("spicy-format")?;
+    let cmd = cmd.stdin(Stdio::piped()).stdout(Stdio::piped());
+
+    let mut child = cmd.spawn()?;
+
+    let mut stdin = child.stdin.as_ref().unwrap();
+    stdin.write("1;\n".as_bytes())?;
+
+    child.wait()?;
+    let mut stdout = String::new();
+    child.stdout.unwrap().read_to_string(&mut stdout)?;
+    assert_eq!(stdout, "1;\n");
+    Ok(())
+}
+
+#[test]
+fn trailing_newline_file() -> Result<()> {
+    let mut input = NamedTempFile::new()?;
+    input.write("1;\n".as_bytes())?;
+
+    let mut cmd = Command::cargo_bin("spicy-format")?;
+    let cmd = cmd.arg(input.path()).stdout(Stdio::piped()).output()?;
+
+    let stdout = String::from_utf8(cmd.stdout)?;
+
+    assert_eq!(stdout, "1;\n");
+    Ok(())
+}