diff --git a/gnu/packages/networking.scm b/gnu/packages/networking.scm
index 2ff252df1f..15dc524d66 100644
--- a/gnu/packages/networking.scm
+++ b/gnu/packages/networking.scm
@@ -4923,24 +4923,23 @@ an implementation of LLDP.  It also supports some proprietary protocols.")
          "15kqaimwb2y8wvzpn73021bvay9mz1gqqfc40gk4hj6f84nz34h1"))))
     (build-system gnu-build-system)
     (arguments
-     (list #:make-flags #~(list (string-append "CC=" #$(cc-for-target)))
-       #:phases
-       #~(modify-phases %standard-phases
-           (delete 'configure)
-           ;; No tests available.
-           (delete 'check)
-           (replace 'install
-             (lambda* (#:key outputs #:allow-other-keys)
-               (let ((bindir (string-append #$output "/bin"))
-                     (mandir (string-append #$output "/share/man/man1"))
-                     (docdir (string-append #$output "/share/doc/hashcash-" #$version)))
-                 ;; Install manually, as we don't need the `sha1' binary
-                 (install-file "hashcash" bindir)
-                 (install-file "hashcash.1" mandir)
-                 (install-file "README" docdir)
-                 (install-file "LICENSE" docdir)
-                 (install-file "CHANGELOG" docdir)))))))
-    (home-page "https://www.hashcash.org/")
+     (list
+      #:tests? #f ;No tests available.
+      #:make-flags
+      #~(list "CFLAGS=-g -O2 -Wno-error=implicit-function-declaration"
+              (string-append "CC=" #$(cc-for-target)))
+      #:phases
+      #~(modify-phases %standard-phases
+          (delete 'configure)
+          (add-after 'unpack 'fix-makefile
+            (lambda _
+              (substitute* "Makefile"
+                (("/usr") #$output)
+                ;; Only install hashcash, as we don't need the `sha1` binary.
+                ((" hashcash sha1 ") " hashcash ")
+                (("sha1-hashcash.1 ") " ")))))))
+    ;; Home page does not have https.
+    (home-page "http://www.hashcash.org/")
     (synopsis "Denial-of-service countermeasure")
     (description "Hashcash is a proof-of-work algorithm, which has been used
 as a denial-of-service countermeasure technique in a number of systems.