diff --git a/release.nix b/release.nix
index b62fd312..71927be7 100644
--- a/release.nix
+++ b/release.nix
@@ -1,5 +1,5 @@
 { hydraSrc ? builtins.fetchGit ./.
-, nixpkgs ? builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-18.03"; }
+, nixpkgs ? builtins.fetchGit { url = https://github.com/NixOS/nixpkgs-channels.git; ref = "nixos-18.03-small"; }
 , officialRelease ? false
 , shell ? false
 }:
diff --git a/src/hydra-eval-jobs/hydra-eval-jobs.cc b/src/hydra-eval-jobs/hydra-eval-jobs.cc
index 87e0e92d..353c737e 100644
--- a/src/hydra-eval-jobs/hydra-eval-jobs.cc
+++ b/src/hydra-eval-jobs/hydra-eval-jobs.cc
@@ -312,6 +312,8 @@ int main(int argc, char * * argv)
             if (status != 0)
                 throw Exit(WIFEXITED(status) ? WEXITSTATUS(status) : 99);
 
+            maxHeapSize = maxHeapSize * 1.1;
+
             lastAttrPath = drainFD(pipe.readSide.get());
         } while (lastAttrPath != "");
     });