diff --git a/pkgs/development/tools/analysis/rr/default.nix b/pkgs/development/tools/analysis/rr/default.nix
index 926aaeb94ccc..26d98ed866b2 100644
--- a/pkgs/development/tools/analysis/rr/default.nix
+++ b/pkgs/development/tools/analysis/rr/default.nix
@@ -11,8 +11,9 @@ stdenv.mkDerivation rec {
     sha256 = "03fl2wgbc1cilaw8hrhfqjsbpi05cid6k4cr3s2vmv5gx0dnrgy4";
   };
 
-  patchPhase = ''
+  postPatch = ''
     substituteInPlace src/Command.cc --replace '_BSD_SOURCE' '_DEFAULT_SOURCE'
+    sed '7i#include "math.h"' -i src/Scheduler.cc
     patchShebangs .
   '';