diff --git a/gnu/packages/photo.scm b/gnu/packages/photo.scm
index 5b5e057b65..09767f464e 100644
--- a/gnu/packages/photo.scm
+++ b/gnu/packages/photo.scm
@@ -486,8 +486,9 @@ photographic equipment.")
              ;; Darktable looks for opencl-c.h in the LLVM dir. Guix installs
              ;; it to the Clang dir. We fix this by patching CMakeLists.txt.
              (substitute* "CMakeLists.txt"
-                          (("\\$\\{LLVM_INSTALL_PREFIX\\}")
-                           (assoc-ref %build-inputs "clang")))))
+               (("\\$\\{LLVM_INSTALL_PREFIX\\}")
+                (assoc-ref %build-inputs "clang")))
+             #t))
          (add-before 'configure 'set-LDFLAGS-and-CPATH
            (lambda* (#:key inputs outputs #:allow-other-keys)
              (setenv "LDFLAGS"