diff --git a/3.0/modules/tagsmap/helpers/tagsmap_event.php b/3.0/modules/tagsmap/helpers/tagsmap_event.php
index 66ed8fd2..b38d9f50 100644
--- a/3.0/modules/tagsmap/helpers/tagsmap_event.php
+++ b/3.0/modules/tagsmap/helpers/tagsmap_event.php
@@ -32,6 +32,12 @@ class tagsmap_event_Core {
     }
   }
 
+  static function pre_deactivate($data) {
+    if ($data->module == "tag") {
+      $data->messages["warn"][] = t("The TagsMap module requires the Tags module.");
+    }
+  }
+
   static function admin_menu($menu, $theme) {
     // Add a link to the TagsMap admin page to the Content menu.
     $menu->get("content_menu")
diff --git a/3.0/modules/tagsmap/helpers/tagsmap_installer.php b/3.0/modules/tagsmap/helpers/tagsmap_installer.php
index 48ad5461..4567d4df 100644
--- a/3.0/modules/tagsmap/helpers/tagsmap_installer.php
+++ b/3.0/modules/tagsmap/helpers/tagsmap_installer.php
@@ -43,6 +43,14 @@ class tagsmap_installer {
     site_status::clear("tagsmap_needs_tag");
   }
 
+  static function can_activate() {
+    $messages = array();
+    if (!module::is_active("tag")) {
+      $messages["warn"][] = t("The TagsMap module requires the Tags module.");
+    }
+    return $messages;
+  }
+
   static function uninstall() {
     // Delete the GPS table before uninstalling.
     $db = Database::instance();
diff --git a/3.1/modules/tagsmap/helpers/tagsmap_event.php b/3.1/modules/tagsmap/helpers/tagsmap_event.php
index 66ed8fd2..b38d9f50 100644
--- a/3.1/modules/tagsmap/helpers/tagsmap_event.php
+++ b/3.1/modules/tagsmap/helpers/tagsmap_event.php
@@ -32,6 +32,12 @@ class tagsmap_event_Core {
     }
   }
 
+  static function pre_deactivate($data) {
+    if ($data->module == "tag") {
+      $data->messages["warn"][] = t("The TagsMap module requires the Tags module.");
+    }
+  }
+
   static function admin_menu($menu, $theme) {
     // Add a link to the TagsMap admin page to the Content menu.
     $menu->get("content_menu")
diff --git a/3.1/modules/tagsmap/helpers/tagsmap_installer.php b/3.1/modules/tagsmap/helpers/tagsmap_installer.php
index 48ad5461..4567d4df 100644
--- a/3.1/modules/tagsmap/helpers/tagsmap_installer.php
+++ b/3.1/modules/tagsmap/helpers/tagsmap_installer.php
@@ -43,6 +43,14 @@ class tagsmap_installer {
     site_status::clear("tagsmap_needs_tag");
   }
 
+  static function can_activate() {
+    $messages = array();
+    if (!module::is_active("tag")) {
+      $messages["warn"][] = t("The TagsMap module requires the Tags module.");
+    }
+    return $messages;
+  }
+
   static function uninstall() {
     // Delete the GPS table before uninstalling.
     $db = Database::instance();