diff --git a/gnu/packages.scm b/gnu/packages.scm
index 61345f75a9..7e5a6d49c2 100644
--- a/gnu/packages.scm
+++ b/gnu/packages.scm
@@ -356,20 +356,24 @@ (define cache
            (find-packages-by-name/direct name version))))
 
 (define (find-best-packages-by-name name version)
-  "If version is #f, return the list of packages named NAME with the highest
-version numbers; otherwise, return the list of packages named NAME and at
-VERSION."
+  "If version is #f, return the list of packages named NAME with only
+packages marked default? or, if none exist, the highest version numbers;
+otherwise, return the list of packages named NAME and at VERSION."
   (if version
       (find-packages-by-name name version)
       (match (find-packages-by-name name)
         (()
          '())
         ((matches ...)
-         ;; Return the subset of MATCHES with the higher version number.
-         (let ((highest (package-version (first matches))))
-           (take-while (lambda (p)
-                         (string=? (package-version p) highest))
-                       matches))))))
+         ;; Return the subset of MATCHES which are marked default or those with
+         ;; the higher version number.
+         (let ((highest (package-version (first matches)))
+               (default (filter (lambda (p) (assoc-ref (package-properties p) 'default?)) matches)))
+           (if (not (null? default))
+               default
+               (take-while (lambda (p)
+                             (string=? (package-version p) highest))
+                           matches)))))))
 
 ;; Prevent Guile 3 from inlining this procedure so we can mock it in tests.
 (set! find-best-packages-by-name find-best-packages-by-name)
diff --git a/gnu/packages/commencement.scm b/gnu/packages/commencement.scm
index b4566b41cc..2d5e0add26 100644
--- a/gnu/packages/commencement.scm
+++ b/gnu/packages/commencement.scm
@@ -3855,7 +3855,10 @@ (define* (make-gcc-toolchain gcc
                 ("libc-static" ,libc "static"))))))
 
 (define-public gcc-toolchain
-  (make-gcc-toolchain gcc-final))
+  (let ((parent (make-gcc-toolchain gcc-final)))
+    (package
+      (inherit parent)
+      (properties (alist-cons 'default? #t (package-properties parent))))))
 
 (define-public gcc-toolchain-4.8
   (make-gcc-toolchain gcc-4.8))