diff --git a/Cargo.lock b/Cargo.lock
index ff07a73..7df5586 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -723,6 +723,12 @@ dependencies = [
  "hashbrown",
 ]
 
+[[package]]
+name = "indoc"
+version = "2.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b248f5224d1d606005e02c97f5aa4e88eeb230488bcc03bc9ca4d7991399f2b5"
+
 [[package]]
 name = "insta"
 version = "1.42.0"
@@ -870,6 +876,7 @@ dependencies = [
  "env_logger",
  "html5ever",
  "indexmap",
+ "indoc",
  "insta",
  "log",
  "mdbook",
diff --git a/Cargo.toml b/Cargo.toml
index c0c4611..5da6d01 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -38,6 +38,7 @@ utf8parse = "0.2.2"
 walkdir = "2.0.0"
 
 [dev-dependencies]
+indoc = "2.0.5"
 insta = { version = "1.36.0" }
 similar = { version = "2.5.0", features = ["text"] }
 tracing = { version = "0.1.0", default-features = false, features = ["std"] }