diff --git a/src/cuirass/base.scm b/src/cuirass/base.scm
index fc3cc1a..3d19bda 100644
--- a/src/cuirass/base.scm
+++ b/src/cuirass/base.scm
@@ -185,9 +185,12 @@ if required.  Return the last commit ID on success, #f otherwise."
                                #:use-substitutes? (%use-substitutes?)
                                #:keep-going? #t)
 
+            (guard (c ((evaluation-error? c)
+                       ;; Report the problem in the log...
+                       #f))
               (let* ((spec* (acons #:current-commit commit spec))
                      (jobs  (evaluate store db spec*)))
-              (build-packages store db jobs))))
+                (build-packages store db jobs)))))
         (db-add-stamp db spec commit))))
 
   (for-each process jobspecs))