diff --git a/docs/UPGRADING.md b/docs/UPGRADING.md
index c047ae5a..01baae1f 100644
--- a/docs/UPGRADING.md
+++ b/docs/UPGRADING.md
@@ -1029,6 +1029,12 @@ The masking API has been removed on **2021-01-01**
 
 ## Deprecated APIs and their replacements
 
+### Leader plugin
+
+The `Leader.inject()` function is deprecated.  Please call `Runtime.handleKeyEvent()` directly instead.
+
+Direct access to the `Leader.time_out` configuration variable is deprecated.  Please use the `Leader.setTimeout(ms)` function instead.
+
 ### Source code and namespace rearrangement
 
 With the move towards a monorepo-based source, some headers have moved to a new location, and plenty of plugins moved to a new namespace (`kaleidoscope::plugin`). This means that the old headers, and some old names are deprecated. The old names no longer work.
diff --git a/plugins/Kaleidoscope-Leader/src/kaleidoscope/plugin/Leader.cpp b/plugins/Kaleidoscope-Leader/src/kaleidoscope/plugin/Leader.cpp
index 3e7c833c..ea737802 100644
--- a/plugins/Kaleidoscope-Leader/src/kaleidoscope/plugin/Leader.cpp
+++ b/plugins/Kaleidoscope-Leader/src/kaleidoscope/plugin/Leader.cpp
@@ -29,7 +29,10 @@ Key Leader::sequence_[LEADER_MAX_SEQUENCE_LENGTH + 1];
 KeyEventTracker Leader::event_tracker_;
 uint8_t Leader::sequence_pos_;
 uint16_t Leader::start_time_ = 0;
+#ifndef NDEPRECATED
 uint16_t Leader::time_out = 1000;
+#endif
+uint16_t Leader::timeout_ = 1000;
 const Leader::dictionary_t *Leader::dictionary;
 
 // --- helpers ---
@@ -82,10 +85,11 @@ void Leader::reset(void) {
   sequence_[0] = Key_NoKey;
 }
 
-// DEPRECATED
+#ifndef NDEPRECATED
 void Leader::inject(Key key, uint8_t key_state) {
   Runtime.handleKeyEvent(KeyEvent(KeyAddr::none(), key_state | INJECTED, key));
 }
+#endif
 
 // --- hooks ---
 EventHandlerResult Leader::onNameQuery() {
@@ -141,8 +145,16 @@ EventHandlerResult Leader::afterEachCycle() {
   if (!isActive())
     return EventHandlerResult::OK;
 
+#ifndef NDEPRECATED
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
   if (Runtime.hasTimeExpired(start_time_, time_out))
     reset();
+#pragma GCC diagnostic pop
+#else
+  if (Runtime.hasTimeExpired(start_time_, timeout_))
+    reset();
+#endif
 
   return EventHandlerResult::OK;
 }
diff --git a/plugins/Kaleidoscope-Leader/src/kaleidoscope/plugin/Leader.h b/plugins/Kaleidoscope-Leader/src/kaleidoscope/plugin/Leader.h
index f84b4752..0b730cbf 100644
--- a/plugins/Kaleidoscope-Leader/src/kaleidoscope/plugin/Leader.h
+++ b/plugins/Kaleidoscope-Leader/src/kaleidoscope/plugin/Leader.h
@@ -21,6 +21,19 @@
 #include "kaleidoscope/KeyEventTracker.h"
 #include "kaleidoscope/plugin.h"
 
+// -----------------------------------------------------------------------------
+// Deprecation warning messages
+#define _DEPRECATED_MESSAGE_LEADER_INJECT                               \
+  "The `Leader.inject()` function is deprecated. Please call\n"         \
+  "`kaleidoscope::Runtime.handleKeyEvent()` directly instead.\n"        \
+  "This function will be removed after 2022-09-01."
+
+#define _DEPRECATED_MESSAGE_LEADER_TIME_OUT                             \
+  "The `Leader.time_out` variable is deprecated. Please use the\n"      \
+  "`Leader.setTimeout()` function instead.\n"                           \
+  "This variable will be removed after 2022-09-01."
+// -----------------------------------------------------------------------------
+
 #define LEADER_MAX_SEQUENCE_LENGTH 4
 
 #define LEAD(n) Key(kaleidoscope::ranges::LEAD_FIRST + n)
@@ -43,9 +56,24 @@ class Leader : public kaleidoscope::Plugin {
   static const dictionary_t *dictionary;
 
   static void reset(void);
+
+#ifndef NDEPRECATED
+  DEPRECATED(LEADER_TIME_OUT)
   static uint16_t time_out;
 
+  DEPRECATED(LEADER_INJECT)
   void inject(Key key, uint8_t key_state);
+#endif
+
+  static void setTimeout(uint16_t timeout) {
+#ifndef NDEPRECATED
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+    time_out = timeout;
+#pragma GCC diagnostic pop
+#endif
+    timeout_ = timeout;
+  }
 
   EventHandlerResult onNameQuery();
   EventHandlerResult onKeyswitchEvent(KeyEvent &event);
@@ -56,6 +84,7 @@ class Leader : public kaleidoscope::Plugin {
   static KeyEventTracker event_tracker_;
   static uint8_t sequence_pos_;
   static uint16_t start_time_;
+  static uint16_t timeout_;
 
   static int8_t lookup(void);
 };