diff --git a/gnu/packages/maths.scm b/gnu/packages/maths.scm
index 82ca9caff3..472f53720c 100644
--- a/gnu/packages/maths.scm
+++ b/gnu/packages/maths.scm
@@ -1697,7 +1697,7 @@ (define-public netcdf
              ;; filenames to avoid unnecessary references to the corresponding
              ;; store items.
              (substitute* "libnetcdf.settings"
-               (("(/gnu/store/)([a-Z0-9]*)" all prefix hash)
+               (("(/gnu/store/)([0-9A-Za-z]*)" all prefix hash)
                 (string-append prefix (string-take hash 10) "...")))
              #t)))