diff --git a/gnu/packages/crates-io.scm b/gnu/packages/crates-io.scm
index dc358877f20e2011ebc2afa758ce4b3fe324c7ee..7fb93494c2e278827c9b17648833c4261dada66e 100644
--- a/gnu/packages/crates-io.scm
+++ b/gnu/packages/crates-io.scm
@@ -4303,18 +4303,19 @@ (define-public rust-heapsize-plugin-0.1
 total runtime size of an object on the heap")
     (license license:mpl2.0)))
 
-(define-public rust-hex-0.3
+(define-public rust-hex-0.4
   (package
     (name "rust-hex")
-    (version "0.3.2")
+    (version "0.4.0")
     (source
       (origin
         (method url-fetch)
         (uri (crate-uri "hex" version))
-        (file-name (string-append name "-" version ".crate"))
+        (file-name
+          (string-append name "-" version ".tar.gz"))
         (sha256
          (base32
-          "0xsdcjiik5j750j67zk42qdnmm4ahirk3gmkmcqgq7qls2jjcl40"))))
+          "0glsfrx2pxfsf6ivxj7vfrvd7g78j4z47ssgm5idm8p376z3jfq2"))))
     (build-system cargo-build-system)
     (arguments '(#:skip-build? #t))
     (home-page "https://github.com/KokaKiwi/rust-hex")
@@ -4324,6 +4325,20 @@ (define-public rust-hex-0.3
     (license (list license:asl2.0
                    license:expat))))
 
+(define-public rust-hex-0.3
+  (package
+    (inherit rust-hex-0.4)
+    (name "rust-hex")
+    (version "0.3.2")
+    (source
+      (origin
+        (method url-fetch)
+        (uri (crate-uri "hex" version))
+        (file-name (string-append name "-" version ".crate"))
+        (sha256
+         (base32
+          "0xsdcjiik5j750j67zk42qdnmm4ahirk3gmkmcqgq7qls2jjcl40"))))))
+
 (define-public rust-hex-literal-0.2
   (package
     (name "rust-hex-literal")