1 files changed, 11 insertions, 0 deletions
diff --git a/pkgs/os-specific/linux/minimal-bootstrap/bash/default.nix b/pkgs/os-specific/linux/minimal-bootstrap/bash/default.nix
index 35c4da7acf9..86fa3a58687 100644
--- a/pkgs/os-specific/linux/minimal-bootstrap/bash/default.nix
+++ b/pkgs/os-specific/linux/minimal-bootstrap/bash/default.nix
@@ -54,6 +54,17 @@ bootBash.runCommand "${pname}-${version}" {
         "-e"
         (builtins.toFile "bash-builder.sh" ''
           export CONFIG_SHELL=$SHELL
+
+          # Normalize the NIX_BUILD_CORES variable. The value might be 0, which
+          # means that we're supposed to try and auto-detect the number of
+          # available CPU cores at run-time.
+          NIX_BUILD_CORES="''${NIX_BUILD_CORES:-1}"
+          if ((NIX_BUILD_CORES <= 0)); then
+            guess=$(nproc 2>/dev/null || true)
+            ((NIX_BUILD_CORES = guess <= 0 ? 1 : guess))
+          fi
+          export NIX_BUILD_CORES
+
           bash -eux $buildCommandPath
         '')
       ];