diff --git a/src/libcmd/activatables.cc b/src/libcmd/activatables.cc
index b2082409d..25bcf23b9 100644
--- a/src/libcmd/activatables.cc
+++ b/src/libcmd/activatables.cc
@@ -1,4 +1,5 @@
 #include "command.hh"
+#include "installable-flake.hh"
 #include "progress-bar.hh"
 
 using namespace nix;