diff --git a/pkgs/applications/science/astronomy/gildas/default.nix b/pkgs/applications/science/astronomy/gildas/default.nix
index d74eee4190d..82575d9c6ff 100644
--- a/pkgs/applications/science/astronomy/gildas/default.nix
+++ b/pkgs/applications/science/astronomy/gildas/default.nix
@@ -12,7 +12,10 @@ stdenv.mkDerivation rec {
   name = "gildas-${version}";
 
   src = fetchurl {
-    url = "http://www.iram.fr/~gildas/dist/gildas-src-${srcVersion}.tar.gz";
+    # For each new release, the upstream developers of Gildas move the
+    # source code of the previous release to a different directory
+    urls = [ "http://www.iram.fr/~gildas/dist/gildas-src-${srcVersion}.tar.gz"
+      "http://www.iram.fr/~gildas/dist/archive/gildas/gildas-src-${srcVersion}.tar.gz" ];
     sha256 = "0mg3wijrj8x1p912vkgrhxbypjx7aj9b1492yxvq2y3fxban6bj1";
   };