diff --git a/gnu/services/authentication.scm b/gnu/services/authentication.scm
index f1ad1b1afe..fbfef2d3d0 100644
--- a/gnu/services/authentication.scm
+++ b/gnu/services/authentication.scm
@@ -504,7 +504,7 @@ password.")
 (define (pam-ldap-pam-service config)
   "Return a PAM service for LDAP authentication."
   (define pam-ldap-module
-    #~(string-append #$(nslcd-configuration-nss-pam-ldapd config)
+    (file-append (nslcd-configuration-nss-pam-ldapd config)
                      "/lib/security/pam_ldap.so"))
   (pam-extension
     (transformer
diff --git a/gnu/services/base.scm b/gnu/services/base.scm
index b557af24af..b3f2d2e8b8 100644
--- a/gnu/services/base.scm
+++ b/gnu/services/base.scm
@@ -3263,7 +3263,7 @@ to handle."
   (define optional-pam-mount
     (pam-entry
      (control "optional")
-     (module #~(string-append #$greetd-pam-mount "/lib/security/pam_mount.so"))
+     (module (file-append greetd-pam-mount "/lib/security/pam_mount.so"))
      (arguments '("disable_interactive"))))
 
   (list
diff --git a/gnu/services/kerberos.scm b/gnu/services/kerberos.scm
index 1a1b37f890..a6f540a9b6 100644
--- a/gnu/services/kerberos.scm
+++ b/gnu/services/kerberos.scm
@@ -432,8 +432,8 @@ generates such a file.  It does not cause any daemon to be started.")))
    (transformer
     (lambda (pam)
       (define pam-krb5-module
-        #~(string-append #$(pam-krb5-configuration-pam-krb5 config)
-                         "/lib/security/pam_krb5.so"))
+        (file-append (pam-krb5-configuration-pam-krb5 config)
+                     "/lib/security/pam_krb5.so"))
 
       (let ((pam-krb5-sufficient
              (pam-entry
diff --git a/gnu/services/pam-mount.scm b/gnu/services/pam-mount.scm
index dbb9d0285f..b3a02e82e9 100644
--- a/gnu/services/pam-mount.scm
+++ b/gnu/services/pam-mount.scm
@@ -94,7 +94,7 @@
   (define optional-pam-mount
     (pam-entry
      (control "optional")
-     (module #~(string-append #$pam-mount "/lib/security/pam_mount.so"))))
+     (module (file-append pam-mount "/lib/security/pam_mount.so"))))
   (list
    (pam-extension
     (transformer