diff --git a/serde_derive/Cargo.toml b/serde_derive/Cargo.toml
index b0a3e55c..393a5e0a 100644
--- a/serde_derive/Cargo.toml
+++ b/serde_derive/Cargo.toml
@@ -37,4 +37,5 @@ rustdoc-args = [
     "--extern-html-root-url=core=https://doc.rust-lang.org",
     "--extern-html-root-url=alloc=https://doc.rust-lang.org",
     "--extern-html-root-url=std=https://doc.rust-lang.org",
+    "--extern-html-root-url=proc_macro=https://doc.rust-lang.org",
 ]
diff --git a/serde_derive_internals/Cargo.toml b/serde_derive_internals/Cargo.toml
index 264803a4..20bdbccc 100644
--- a/serde_derive_internals/Cargo.toml
+++ b/serde_derive_internals/Cargo.toml
@@ -27,4 +27,5 @@ rustdoc-args = [
     "--extern-html-root-url=core=https://doc.rust-lang.org",
     "--extern-html-root-url=alloc=https://doc.rust-lang.org",
     "--extern-html-root-url=std=https://doc.rust-lang.org",
+    "--extern-html-root-url=proc_macro=https://doc.rust-lang.org",
 ]