diff --git a/gnu/packages/crates-io.scm b/gnu/packages/crates-io.scm
index f2618019e5..0f00f0a3df 100644
--- a/gnu/packages/crates-io.scm
+++ b/gnu/packages/crates-io.scm
@@ -8827,6 +8827,26 @@ (define-public rust-proc-macro-hack-0.5
      "Procedural macros in expression position.")
     (license (list license:expat license:asl2.0))))
 
+(define-public rust-proc-macro-hack-impl-0.4
+  (package
+    (name "rust-proc-macro-hack-impl")
+    (version "0.4.2")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (crate-uri "proc-macro-hack-impl" version))
+       (file-name
+        (string-append name "-" version ".tar.gz"))
+       (sha256
+        (base32
+         "0hk8g6s0zsi1ps0w48la2s8q5iqq42g8jfrgq3l2v04l2p5pvi1q"))))
+    (build-system cargo-build-system)
+    (home-page "https://github.com/dtolnay/proc-macro-hack")
+    (synopsis "Procedural functionlike!() macros using only Macros 1.1")
+    (description
+     "Procedural functionlike!() macros using only Macros 1.1.")
+    (license (list license:expat license:asl2.0))))
+
 (define-public rust-proc-macro-nested-0.1
   (package
     (name "rust-proc-macro-nested")