diff --git a/src/libstore/globals.hh b/src/libstore/globals.hh
index dfe25f31726..50cdf9ffe9d 100644
--- a/src/libstore/globals.hh
+++ b/src/libstore/globals.hh
@@ -16,6 +16,11 @@ namespace nix {
 
 typedef enum { smEnabled, smRelaxed, smDisabled } SandboxMode;
 
+template<> SandboxMode BaseSetting<SandboxMode>::parse(const std::string & str) const;
+template<> struct BaseSetting<SandboxMode>::trait;
+template<> std::string BaseSetting<SandboxMode>::to_string() const;
+template<> void BaseSetting<SandboxMode>::convertToArg(Args & args, const std::string & category);
+
 struct MaxBuildJobsSetting : public BaseSetting<unsigned int>
 {
     MaxBuildJobsSetting(Config * options,