4 files changed, 40 insertions, 7 deletions
diff --git a/src/nvim/api/private/helpers.c b/src/nvim/api/private/helpers.c
index b888d09343..73b5489d5c 100644
--- a/src/nvim/api/private/helpers.c
+++ b/src/nvim/api/private/helpers.c
@@ -218,6 +218,8 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del, bool retva
     return rv;
   }
 
+  bool watched = tv_dict_is_watched(dict);
+
   if (del) {
     // Delete the key
     if (di == NULL) {
@@ -225,6 +227,10 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del, bool retva
       api_set_error(err, kErrorTypeValidation, "Key not found: %s",
                     key.data);
     } else {
+      // Notify watchers
+      if (watched) {
+        tv_dict_watcher_notify(dict, key.data, NULL, &di->di_tv);
+      }
       // Return the old value
       if (retval) {
         rv = vim_to_object(&di->di_tv);
@@ -241,11 +247,16 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del, bool retva
       return rv;
     }
 
+    typval_T oldtv = TV_INITIAL_VALUE;
+
     if (di == NULL) {
       // Need to create an entry
       di = tv_dict_item_alloc_len(key.data, key.size);
       tv_dict_add(dict, di);
     } else {
+      if (watched) {
+        tv_copy(&di->di_tv, &oldtv);
+      }
       // Return the old value
       if (retval) {
         rv = vim_to_object(&di->di_tv);
@@ -255,6 +266,13 @@ Object dict_set_var(dict_T *dict, String key, Object value, bool del, bool retva
 
     // Update the value
     tv_copy(&tv, &di->di_tv);
+
+    // Notify watchers
+    if (watched) {
+      tv_dict_watcher_notify(dict, key.data, &tv, &oldtv);
+      tv_clear(&oldtv);
+    }
+
     // Clear the temporary variable
     tv_clear(&tv);
   }
diff --git a/src/nvim/eval/typval.c b/src/nvim/eval/typval.c
index f9aed7a966..5639414dad 100644
--- a/src/nvim/eval/typval.c
+++ b/src/nvim/eval/typval.c
@@ -1781,7 +1781,7 @@ void tv_dict_watcher_notify(dict_T *const dict, const char *const key, typval_T
     tv_dict_add(argv[2].vval.v_dict, v);
   }
 
-  if (oldtv) {
+  if (oldtv && oldtv->v_type != VAR_UNKNOWN) {
     dictitem_T *const v = tv_dict_item_alloc_len(S_LEN("old"));
     tv_copy(oldtv, &v->di_tv);
     tv_dict_add(argv[2].vval.v_dict, v);
diff --git a/src/nvim/eval/vars.c b/src/nvim/eval/vars.c
index 1c07fc4d45..4d7214205d 100644
--- a/src/nvim/eval/vars.c
+++ b/src/nvim/eval/vars.c
@@ -1348,12 +1348,8 @@ void set_var_const(const char *name, const size_t name_len, typval_T *const tv,
   }
 
   if (watched) {
-    if (oldtv.v_type == VAR_UNKNOWN) {
-      tv_dict_watcher_notify(dict, (char *)v->di_key, &v->di_tv, NULL);
-    } else {
-      tv_dict_watcher_notify(dict, (char *)v->di_key, &v->di_tv, &oldtv);
-      tv_clear(&oldtv);
-    }
+    tv_dict_watcher_notify(dict, (char *)v->di_key, &v->di_tv, &oldtv);
+    tv_clear(&oldtv);
   }
 
   if (is_const) {
diff --git a/src/nvim/lua/stdlib.c b/src/nvim/lua/stdlib.c
index 9b1890403e..498f956ed9 100644
--- a/src/nvim/lua/stdlib.c
+++ b/src/nvim/lua/stdlib.c
@@ -369,12 +369,19 @@ int nlua_setvar(lua_State *lstate)
     return 0;
   }
 
+  bool watched = tv_dict_is_watched(dict);
+
   if (del) {
     // Delete the key
     if (di == NULL) {
       // Doesn't exist, nothing to do
       return 0;
     } else {
+      // Notify watchers
+      if (watched) {
+        tv_dict_watcher_notify(dict, key.data, NULL, &di->di_tv);
+      }
+
       // Delete the entry
       tv_dict_item_remove(dict, di);
     }
@@ -388,17 +395,29 @@ int nlua_setvar(lua_State *lstate)
       return luaL_error(lstate, "Couldn't convert lua value");
     }
 
+    typval_T oldtv = TV_INITIAL_VALUE;
+
     if (di == NULL) {
       // Need to create an entry
       di = tv_dict_item_alloc_len(key.data, key.size);
       tv_dict_add(dict, di);
     } else {
+      if (watched) {
+        tv_copy(&di->di_tv, &oldtv);
+      }
       // Clear the old value
       tv_clear(&di->di_tv);
     }
 
     // Update the value
     tv_copy(&tv, &di->di_tv);
+
+    // Notify watchers
+    if (watched) {
+      tv_dict_watcher_notify(dict, key.data, &tv, &oldtv);
+      tv_clear(&oldtv);
+    }
+
     // Clear the temporary variable
     tv_clear(&tv);
   }