diff --git a/NixSupport/default.nix b/NixSupport/default.nix
index 75c1feee5..5a0fa1975 100644
--- a/NixSupport/default.nix
+++ b/NixSupport/default.nix
@@ -96,9 +96,12 @@ in
         src = pkgs.nix-gitignore.gitignoreSource [] projectPath;
         buildInputs = builtins.concatLists [ [allHaskellPackages] allNativePackages ];
         nativeBuildInputs = builtins.concatLists [
-          [ pkgs.makeWrapper ]
+          [ pkgs.makeWrapper
+            pkgs.cacert # Needed for npm install to work from within the IHP build process
+          ]
           (if includeDevTools then [(pkgs.postgresql_13.withPackages postgresExtensions)] else [])
         ];
         shellHook = "eval $(egrep ^export ${allHaskellPackages}/bin/ghc)";
         enableParallelBuilding = true;
+        impureEnvVars = pkgs.lib.fetchers.proxyImpureEnvVars; # Needed for npm install to work from within the IHP build process
     }