diff --git a/pkgs/tools/system/gdmap/default.nix b/pkgs/tools/system/gdmap/default.nix
index 72938216b0a4..0c254bb28545 100644
--- a/pkgs/tools/system/gdmap/default.nix
+++ b/pkgs/tools/system/gdmap/default.nix
@@ -15,6 +15,10 @@ stdenv.mkDerivation rec {
 
   hardeningDisable = [ "format" ];
 
+  NIX_LDFLAGS = [
+    "-lm"
+  ];
+
   meta = with stdenv.lib; {
     homepage = http://gdmap.sourceforge.net;
     description = "Recursive rectangle map of disk usage";