diff --git a/pkgs/build-support/rust/lib/default.nix b/pkgs/build-support/rust/lib/default.nix
index c23f779bfe5d..9cba6694cb19 100644
--- a/pkgs/build-support/rust/lib/default.nix
+++ b/pkgs/build-support/rust/lib/default.nix
@@ -44,6 +44,16 @@ rec {
     #
     setEnv = ''
     env \
+      "CC_${stdenv.buildPlatform.rust.cargoEnvVarTarget}=${ccForBuild}" \
+      "CXX_${stdenv.buildPlatform.rust.cargoEnvVarTarget}=${cxxForBuild}" \
+      "CARGO_TARGET_${stdenv.buildPlatform.rust.cargoEnvVarTarget}_LINKER=${ccForBuild}" \
+      "CARGO_BUILD_TARGET=${rustBuildPlatform}" \
+      "HOST_CC=${pkgsBuildHost.stdenv.cc}/bin/cc" \
+      "HOST_CXX=${pkgsBuildHost.stdenv.cc}/bin/c++" \
+    '' + ''
+      "CC_${stdenv.hostPlatform.rust.cargoEnvVarTarget}=${ccForHost}" \
+      "CXX_${stdenv.hostPlatform.rust.cargoEnvVarTarget}=${cxxForHost}" \
+      "CARGO_TARGET_${stdenv.hostPlatform.rust.cargoEnvVarTarget}_LINKER=${ccForHost}" \
     ''
     # Due to a bug in how splicing and pkgsTargetTarget works, in
     # situations where pkgsTargetTarget is irrelevant
@@ -54,17 +64,6 @@ rec {
       "CC_${stdenv.targetPlatform.rust.cargoEnvVarTarget}=${ccForTarget}" \
       "CXX_${stdenv.targetPlatform.rust.cargoEnvVarTarget}=${cxxForTarget}" \
       "CARGO_TARGET_${stdenv.targetPlatform.rust.cargoEnvVarTarget}_LINKER=${ccForTarget}" \
-    '' + ''
-      "CC_${stdenv.hostPlatform.rust.cargoEnvVarTarget}=${ccForHost}" \
-      "CXX_${stdenv.hostPlatform.rust.cargoEnvVarTarget}=${cxxForHost}" \
-      "CARGO_TARGET_${stdenv.hostPlatform.rust.cargoEnvVarTarget}_LINKER=${ccForHost}" \
-    '' + ''
-      "CC_${stdenv.buildPlatform.rust.cargoEnvVarTarget}=${ccForBuild}" \
-      "CXX_${stdenv.buildPlatform.rust.cargoEnvVarTarget}=${cxxForBuild}" \
-      "CARGO_TARGET_${stdenv.buildPlatform.rust.cargoEnvVarTarget}_LINKER=${ccForBuild}" \
-      "CARGO_BUILD_TARGET=${rustBuildPlatform}" \
-      "HOST_CC=${pkgsBuildHost.stdenv.cc}/bin/cc" \
-      "HOST_CXX=${pkgsBuildHost.stdenv.cc}/bin/c++" \
     '';
   };
 } // lib.mapAttrs (old: new: platform: