diff --git a/src/nix-collect-garbage/nix-collect-garbage.cc b/src/nix-collect-garbage/nix-collect-garbage.cc
index bb4789aea..5a72cb712 100644
--- a/src/nix-collect-garbage/nix-collect-garbage.cc
+++ b/src/nix-collect-garbage/nix-collect-garbage.cc
@@ -4,6 +4,7 @@
 #include "globals.hh"
 
 #include <iostream>
+#include <cerrno>
 
 using namespace nix;