diff --git a/gnu/packages/python.scm b/gnu/packages/python.scm
index 07725c727a..7f7fa388a1 100644
--- a/gnu/packages/python.scm
+++ b/gnu/packages/python.scm
@@ -164,7 +164,7 @@
              ;; Use zero as the timestamp in .pyc files so that builds are
              ;; deterministic.  TODO: Remove it when this variable is set in
              ;; gnu-build-system.scm.
-             (setenv "SOURCE_DATE_EPOCH" "0")
+             (setenv "SOURCE_DATE_EPOCH" "1")
              #t))
           (add-before
            'check 'pre-check
diff --git a/guix/build/python-build-system.scm b/guix/build/python-build-system.scm
index 6775cc4396..8025b7fec6 100644
--- a/guix/build/python-build-system.scm
+++ b/guix/build/python-build-system.scm
@@ -140,7 +140,7 @@ installed with setuptools."
   "Set the 'SOURCE_DATE_EPOCH' environment variable."
   ;; Use zero as the timestamp in .pyc files so that builds are deterministic.
   ;; TODO: Remove it when this variable is set in GNU:%STANDARD-PHASES.
-  (setenv "SOURCE_DATE_EPOCH" "0"))
+  (setenv "SOURCE_DATE_EPOCH" "1"))
 
 (define %standard-phases
   ;; 'configure' and 'build' phases are not needed.  Everything is done during