diff --git a/pkgs/servers/mail/mlmmj/default.nix b/pkgs/servers/mail/mlmmj/default.nix
index e9d3bf9c8f32..89e142b04f98 100644
--- a/pkgs/servers/mail/mlmmj/default.nix
+++ b/pkgs/servers/mail/mlmmj/default.nix
@@ -10,6 +10,12 @@ stdenv.mkDerivation rec {
     sha256 = "1sghqvwizvm1a9w56r34qy5njaq1c26bagj85r60h32gh3fx02bn";
   };
 
+  # Workaround build failure on -fno-common toolchains like upstream
+  # gcc-10. Otherwise build fails as:
+  #   ld: getlistdelim.o:/build/mlmmj-1.3.0/src/../include/mlmmj.h:84: multiple definition of
+  #     `subtype_strs'; mlmmj-send.o:/build/mlmmj-1.3.0/src/../include/mlmmj.h:84: first defined here
+  NIX_CFLAGS_COMPILE = "-fcommon";
+
   postInstall = ''
     # grab all documentation files
     docfiles=$(find -maxdepth 1 -name "[[:upper:]][[:upper:]]*")