diff --git a/pkgs/stdenv/adapters.nix b/pkgs/stdenv/adapters.nix
index eaf497f335f5..0c5645e5a487 100644
--- a/pkgs/stdenv/adapters.nix
+++ b/pkgs/stdenv/adapters.nix
@@ -176,7 +176,7 @@ rec {
     stdenv.override (old: {
       mkDerivationFromStdenv = extendMkDerivationArgs old (args: {
         dontStrip = true;
-        env = (args.env or {}) // { NIX_CFLAGS_COMPILE = toString (args.NIX_CFLAGS_COMPILE or "") + " -ggdb -Og"; };
+        env = (args.env or {}) // { NIX_CFLAGS_COMPILE = toString (args.env.NIX_CFLAGS_COMPILE or "") + " -ggdb -Og"; };
       });
     });
 
@@ -219,7 +219,7 @@ rec {
   impureUseNativeOptimizations = stdenv:
     stdenv.override (old: {
       mkDerivationFromStdenv = extendMkDerivationArgs old (args: {
-        env = (args.env or {}) // { NIX_CFLAGS_COMPILE = toString (args.NIX_CFLAGS_COMPILE or "") + " -march=native"; };
+        env = (args.env or {}) // { NIX_CFLAGS_COMPILE = toString (args.env.NIX_CFLAGS_COMPILE or "") + " -march=native"; };
 
         NIX_ENFORCE_NO_NATIVE = false;
 
@@ -245,7 +245,7 @@ rec {
   withCFlags = compilerFlags: stdenv:
     stdenv.override (old: {
       mkDerivationFromStdenv = extendMkDerivationArgs old (args: {
-        env = (args.env or {}) // { NIX_CFLAGS_COMPILE = toString (args.NIX_CFLAGS_COMPILE or "") + " ${toString compilerFlags}"; };
+        env = (args.env or {}) // { NIX_CFLAGS_COMPILE = toString (args.env.NIX_CFLAGS_COMPILE or "") + " ${toString compilerFlags}"; };
       });
     });
 }