diff --git a/nix/libstore/optimise-store.cc b/nix/libstore/optimise-store.cc
index 8ba9d1a263..4ea27fdebb 100644
--- a/nix/libstore/optimise-store.cc
+++ b/nix/libstore/optimise-store.cc
@@ -4,6 +4,7 @@
 #include "local-store.hh"
 #include "globals.hh"
 
+#include <stdlib.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
diff --git a/nix/libstore/remote-store.cc b/nix/libstore/remote-store.cc
index 706904c74d..55156a9978 100644
--- a/nix/libstore/remote-store.cc
+++ b/nix/libstore/remote-store.cc
@@ -10,6 +10,7 @@
 #include <sys/stat.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <errno.h>
 #include <fcntl.h>
 
 #include <iostream>