diff --git a/pkgs/development/compilers/alan/2.nix b/pkgs/development/compilers/alan/2.nix
index e24cc35a9d7..7329a0115d8 100644
--- a/pkgs/development/compilers/alan/2.nix
+++ b/pkgs/development/compilers/alan/2.nix
@@ -14,6 +14,10 @@ stdenv.mkDerivation rec {
 
   makefile = "Makefile.unix";
 
+  # Add a workarounf for -fno-common tollchains like upstream gcc-10.
+  # alan-3 is already fixed, but the backport is nontrivial.
+  NIX_CFLAGS_COMPILE = "-fcommon";
+
   installPhase = ''
     mkdir -p $out/bin $out/share/alan2
     cp compiler/alan $out/bin/alan2