diff --git a/gnu/packages/kde-frameworks.scm b/gnu/packages/kde-frameworks.scm
index d1356931a1..f9e43583de 100644
--- a/gnu/packages/kde-frameworks.scm
+++ b/gnu/packages/kde-frameworks.scm
@@ -231,18 +231,18 @@ (define-public phonon
     (inputs
      (list qtbase-5))
     (arguments
-     `(#:configure-flags
-       '("-DCMAKE_CXX_FLAGS=-fPIC"
-         "-DPHONON_BUILD_PHONON4QT5=ON")
-       #:phases
-       (modify-phases %standard-phases
-         (add-before 'install 'patch-installdir
-           (lambda* (#:key inputs outputs #:allow-other-keys)
-             (let ((regex (string-append "(INSTALL DESTINATION \")"
-                                         (assoc-ref inputs "qtbase"))))
-               (substitute* "cmake_install.cmake"
-                 ((regex all dest)
-                  (string-append dest (assoc-ref outputs "out"))))))))))
+     (list #:configure-flags
+           #~'("-DCMAKE_CXX_FLAGS=-fPIC"
+               "-DPHONON_BUILD_PHONON4QT5=ON")
+           #:phases
+           #~(modify-phases %standard-phases
+               (add-before 'install 'patch-installdir
+                 (lambda* (#:key inputs outputs #:allow-other-keys)
+                   (let ((regex (string-append "(INSTALL DESTINATION \")"
+                                               #$(this-package-input "qtbase"))))
+                     (substitute* "cmake_install.cmake"
+                       ((regex all dest)
+                        (string-append dest #$output)))))))))
     (home-page "https://community.kde.org/Phonon")
     (synopsis "KDE's multimedia library")
     (description "KDE's multimedia library.")