diff --git a/pkgs/development/libraries/aterm/2.4.2-fixes.nix b/pkgs/development/libraries/aterm/2.4.2-fixes.nix
index a160d5cd121..b02da9be1ac 100644
--- a/pkgs/development/libraries/aterm/2.4.2-fixes.nix
+++ b/pkgs/development/libraries/aterm/2.4.2-fixes.nix
@@ -12,6 +12,12 @@ stdenv.mkDerivation {
     # Fix for http://bugzilla.sen.cwi.nl:8080/show_bug.cgi?id=841
     ./max-long.patch
   ];
+
+  # There are apparently still some aliasing bugs left in
+  # aterm-2.4.2-fixes-r2 (in AT_setAnnotations to be precise), but
+  # under my reading of the C standard it should be fine. Anyway, just
+  # disable strict aliasing.
+  NIX_CFLAGS_COMPILE = "-fno-strict-aliasing";
   
   doCheck = true;
 
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 504b7fc8255..8e29f29d69a 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -8499,7 +8499,7 @@ let
 
   nix = makeOverridable (import ../tools/package-management/nix) {
     inherit fetchurl stdenv perl curl bzip2 openssl;
-    aterm = aterm25;
+    aterm = aterm242fixes;
     db4 = db45;
     supportOldDBs = getPkgConfig "nix" "OldDBSupport" true;
     storeDir = getPkgConfig "nix" "storeDir" "/nix/store";
@@ -8509,7 +8509,7 @@ let
   # The bleeding edge.
   nixUnstable = makeOverridable (import ../tools/package-management/nix/unstable.nix) {
     inherit fetchurl stdenv perl curl bzip2 openssl;
-    aterm = aterm25;
+    aterm = aterm242fixes;
     storeDir = getPkgConfig "nix" "storeDir" "/nix/store";
     stateDir = getPkgConfig "nix" "stateDir" "/nix/var";
   };