diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 9701af8079e..993876c6d10 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -103,7 +103,7 @@ typedef std::shared_ptr<Goal> GoalPtr;
 typedef std::weak_ptr<Goal> WeakGoalPtr;
 
 struct CompareGoalPtrs {
-    bool operator() (const GoalPtr & a, const GoalPtr & b);
+    bool operator() (const GoalPtr & a, const GoalPtr & b) const;
 };
 
 /* Set of goals. */
@@ -201,7 +201,7 @@ protected:
 };
 
 
-bool CompareGoalPtrs::operator() (const GoalPtr & a, const GoalPtr & b) {
+bool CompareGoalPtrs::operator() (const GoalPtr & a, const GoalPtr & b) const {
     string s1 = a->key();
     string s2 = b->key();
     return s1 < s2;
diff --git a/nix/libstore/store-api.hh b/nix/libstore/store-api.hh
index 82a79e50e2c..32a8f2c795f 100644
--- a/nix/libstore/store-api.hh
+++ b/nix/libstore/store-api.hh
@@ -4,6 +4,7 @@
 #include "serialise.hh"
 
 #include <string>
+#include <cstdint>
 #include <map>
 #include <memory>