diff --git a/src/utils/fs.rs b/crates/mdbook-core/src/utils/fs.rs
similarity index 100%
rename from src/utils/fs.rs
rename to crates/mdbook-core/src/utils/fs.rs
diff --git a/src/utils/mod.rs b/crates/mdbook-core/src/utils/mod.rs
similarity index 100%
rename from src/utils/mod.rs
rename to crates/mdbook-core/src/utils/mod.rs
diff --git a/src/utils/string.rs b/crates/mdbook-core/src/utils/string.rs
similarity index 100%
rename from src/utils/string.rs
rename to crates/mdbook-core/src/utils/string.rs
diff --git a/src/utils/toml_ext.rs b/crates/mdbook-core/src/utils/toml_ext.rs
similarity index 100%
rename from src/utils/toml_ext.rs
rename to crates/mdbook-core/src/utils/toml_ext.rs