diff --git a/src/player.cc b/src/player.cc
index cb7fbc4..0c38fcb 100644
--- a/src/player.cc
+++ b/src/player.cc
@@ -344,3 +344,7 @@ void player_base::inventory::print(output *out, unsigned long known_potions) {
                                 static_cast<int>(curr) + INV_TOP + INV_Y_OFFSET},
                                "->");
 }
+
+void player_base::set_potion_known(const potion_type &type) {
+        known_potions |= 1 << type;
+}
diff --git a/src/player.h b/src/player.h
index 8835e1d..5029b78 100644
--- a/src/player.h
+++ b/src/player.h
@@ -61,6 +61,8 @@ public:
 
         long_result throw_potion(level *lvl,
                                  std::unique_ptr<potion> p, direction dir);
+
+        void set_potion_known(const potion_type &type);
 };
 
 #endif