diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index 8216174..f40cd7e 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,5 +1,5 @@
 {
   "git": {
-    "sha1": "d29a20e44207f915f42e6d1668d2864b0152e5a8"
+    "sha1": "8a3cec3cfc7b8417ef8cc2970f7de27ff2b6a023"
   }
 }
diff --git a/Cargo.toml b/Cargo.toml
index f417011..0e57e36 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,8 +12,10 @@
 
 [package]
 name = "proc-macro-nested"
-version = "0.1.4"
+version = "0.1.6"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 description = "Support for nested proc-macro-hack invocations"
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/dtolnay/proc-macro-hack"
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
index 3d64155..fd0fa99 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -1,7 +1,10 @@
 [package]
 name = "proc-macro-nested"
-version = "0.1.4"
+version = "0.1.6"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 license = "MIT OR Apache-2.0"
 description = "Support for nested proc-macro-hack invocations"
 repository = "https://github.com/dtolnay/proc-macro-hack"
+
+[package.metadata.docs.rs]
+targets = ["x86_64-unknown-linux-gnu"]
diff --git a/METADATA b/METADATA
index 1bef54b..a328cee 100644
--- a/METADATA
+++ b/METADATA
@@ -1,7 +1,5 @@
 name: "proc-macro-nested"
-description:
-    "Support for nested proc-macro-hack invocations"
-
+description: "Support for nested proc-macro-hack invocations"
 third_party {
   url {
     type: HOMEPAGE
@@ -11,7 +9,11 @@
     type: GIT
     value: "https://github.com/dtolnay/proc-macro-hack"
   }
-  version: "0.1.4"
-  last_upgrade_date { year: 2020 month: 3 day: 17 }
+  version: "0.1.6"
   license_type: NOTICE
+  last_upgrade_date {
+    year: 2020
+    month: 7
+    day: 10
+  }
 }
diff --git a/build.rs b/build.rs
index b4aec63..ef56f8e 100644
--- a/build.rs
+++ b/build.rs
@@ -1,6 +1,5 @@
 use std::env;
-use std::fs::File;
-use std::io::Write;
+use std::fs;
 use std::iter;
 use std::path::Path;
 
@@ -16,26 +15,32 @@
 */
 
 fn main() {
-    let out_dir = env::var("OUT_DIR").unwrap();
-    let dest_path = Path::new(&out_dir).join("count.rs");
-    let mut f = File::create(&dest_path).unwrap();
+    // Tell Cargo not to rerun on src/lib.rs changes.
+    println!("cargo:rerun-if-changed=build.rs");
 
     let mut content = String::new();
-    content += "
-        #[doc(hidden)]
-        #[macro_export]
-        macro_rules! count {
-    ";
+    content += "#[doc(hidden)]\n";
+    content += "#[macro_export]\n";
+    content += "macro_rules! count {\n";
     for i in 0..=64 {
         let bangs = iter::repeat("!").take(i).collect::<String>();
-        content += &format!("({}) => {{ proc_macro_call_{}!() }};", bangs, i);
+        content += &format!("    ({}) => {{ proc_macro_call_{}!() }};\n", bangs, i);
     }
-    content += "
-            ($(!)+) => {
-                compile_error!(\"this macro does not support >64 nested macro invocations\")
-            };
-        }
-    ";
+    content += "    ($(!)+) => {\n";
+    content += "        compile_error! { \"this macro does not support >64 nested macro invocations\" }\n";
+    content += "    };\n";
+    content += "}\n";
 
-    f.write_all(content.as_bytes()).unwrap();
+    let content = content.as_bytes();
+    let out_dir = env::var("OUT_DIR").unwrap();
+    let ref dest_path = Path::new(&out_dir).join("count.rs");
+
+    // Avoid bumping filetime if content is up to date. Possibly related to
+    // https://github.com/dtolnay/proc-macro-hack/issues/56 ...?
+    if fs::read(dest_path)
+        .map(|existing| existing != content)
+        .unwrap_or(true)
+    {
+        fs::write(dest_path, content).unwrap();
+    }
 }
diff --git a/out/count.rs b/out/count.rs
index de54fc6..41f84a9 100644
--- a/out/count.rs
+++ b/out/count.rs
@@ -1,10 +1,72 @@
-
-        #[doc(hidden)]
-        #[macro_export]
-        macro_rules! count {
-    () => { proc_macro_call_0!() };(!) => { proc_macro_call_1!() };(!!) => { proc_macro_call_2!() };(!!!) => { proc_macro_call_3!() };(!!!!) => { proc_macro_call_4!() };(!!!!!) => { proc_macro_call_5!() };(!!!!!!) => { proc_macro_call_6!() };(!!!!!!!) => { proc_macro_call_7!() };(!!!!!!!!) => { proc_macro_call_8!() };(!!!!!!!!!) => { proc_macro_call_9!() };(!!!!!!!!!!) => { proc_macro_call_10!() };(!!!!!!!!!!!) => { proc_macro_call_11!() };(!!!!!!!!!!!!) => { proc_macro_call_12!() };(!!!!!!!!!!!!!) => { proc_macro_call_13!() };(!!!!!!!!!!!!!!) => { proc_macro_call_14!() };(!!!!!!!!!!!!!!!) => { proc_macro_call_15!() };(!!!!!!!!!!!!!!!!) => { proc_macro_call_16!() };(!!!!!!!!!!!!!!!!!) => { proc_macro_call_17!() };(!!!!!!!!!!!!!!!!!!) => { proc_macro_call_18!() };(!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_19!() };(!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_20!() };(!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_21!() };(!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_22!() };(!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_23!() };(!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_24!() };(!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_25!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_26!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_27!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_28!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_29!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_30!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_31!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_32!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_33!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_34!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_35!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_36!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_37!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_38!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_39!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_40!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_41!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_42!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_43!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_44!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_45!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_46!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_47!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_48!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_49!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_50!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_51!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_52!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_53!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_54!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_55!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_56!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_57!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_58!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_59!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_60!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_61!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_62!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_63!() };(!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_64!() };
-            ($(!)+) => {
-                compile_error!("this macro does not support >64 nested macro invocations")
-            };
-        }
-    
\ No newline at end of file
+#[doc(hidden)]
+#[macro_export]
+macro_rules! count {
+    () => { proc_macro_call_0!() };
+    (!) => { proc_macro_call_1!() };
+    (!!) => { proc_macro_call_2!() };
+    (!!!) => { proc_macro_call_3!() };
+    (!!!!) => { proc_macro_call_4!() };
+    (!!!!!) => { proc_macro_call_5!() };
+    (!!!!!!) => { proc_macro_call_6!() };
+    (!!!!!!!) => { proc_macro_call_7!() };
+    (!!!!!!!!) => { proc_macro_call_8!() };
+    (!!!!!!!!!) => { proc_macro_call_9!() };
+    (!!!!!!!!!!) => { proc_macro_call_10!() };
+    (!!!!!!!!!!!) => { proc_macro_call_11!() };
+    (!!!!!!!!!!!!) => { proc_macro_call_12!() };
+    (!!!!!!!!!!!!!) => { proc_macro_call_13!() };
+    (!!!!!!!!!!!!!!) => { proc_macro_call_14!() };
+    (!!!!!!!!!!!!!!!) => { proc_macro_call_15!() };
+    (!!!!!!!!!!!!!!!!) => { proc_macro_call_16!() };
+    (!!!!!!!!!!!!!!!!!) => { proc_macro_call_17!() };
+    (!!!!!!!!!!!!!!!!!!) => { proc_macro_call_18!() };
+    (!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_19!() };
+    (!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_20!() };
+    (!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_21!() };
+    (!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_22!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_23!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_24!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_25!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_26!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_27!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_28!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_29!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_30!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_31!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_32!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_33!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_34!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_35!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_36!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_37!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_38!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_39!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_40!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_41!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_42!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_43!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_44!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_45!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_46!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_47!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_48!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_49!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_50!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_51!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_52!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_53!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_54!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_55!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_56!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_57!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_58!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_59!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_60!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_61!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_62!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_63!() };
+    (!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!) => { proc_macro_call_64!() };
+    ($(!)+) => {
+        compile_error! { "this macro does not support >64 nested macro invocations" }
+    };
+}