diff --git a/lib/tower.ex b/lib/tower.ex
index 4758a61..0dbd221 100644
--- a/lib/tower.ex
+++ b/lib/tower.ex
@@ -7,30 +7,40 @@ defmodule Tower do
 
   @default_reporters [Tower.EphemeralReporter]
 
+  @spec attach() :: :ok
   def attach do
     :ok = Tower.LoggerHandler.attach()
   end
 
+  @spec detach() :: :ok
   def detach do
     :ok = Tower.LoggerHandler.detach()
   end
 
+  @spec handle_exception(Exception.t(), Exception.stacktrace()) :: :ok
+  @spec handle_exception(Exception.t(), Exception.stacktrace(), Keyword.t()) :: :ok
   def handle_exception(exception, stacktrace, options \\ [])
       when is_exception(exception) and is_list(stacktrace) do
     Event.from_exception(exception, stacktrace, options)
     |> report_event()
   end
 
+  @spec handle_throw(term(), Exception.stacktrace()) :: :ok
+  @spec handle_throw(term(), Exception.stacktrace(), Keyword.t()) :: :ok
   def handle_throw(reason, stacktrace, options \\ []) do
     Event.from_throw(reason, stacktrace, options)
     |> report_event()
   end
 
+  @spec handle_exit(term(), Exception.stacktrace()) :: :ok
+  @spec handle_exit(term(), Exception.stacktrace(), Keyword.t()) :: :ok
   def handle_exit(reason, stacktrace, options \\ []) do
     Event.from_exit(reason, stacktrace, options)
     |> report_event()
   end
 
+  @spec handle_message(:logger.level(), term()) :: :ok
+  @spec handle_message(:logger.level(), term(), Keyword.t()) :: :ok
   def handle_message(level, message, options \\ []) do
     Event.from_message(level, message, options)
     |> report_event()
diff --git a/lib/tower/event.ex b/lib/tower/event.ex
index d19ff3d..34376af 100644
--- a/lib/tower/event.ex
+++ b/lib/tower/event.ex
@@ -12,6 +12,8 @@ defmodule Tower.Event do
           metadata: metadata()
         }
 
+  @spec from_exception(Exception.t(), Exception.stacktrace()) :: t()
+  @spec from_exception(Exception.t(), Exception.stacktrace(), Keyword.t()) :: t()
   def from_exception(exception, stacktrace, options \\ []) do
     log_event = Keyword.get(options, :log_event)
 
@@ -27,6 +29,8 @@ defmodule Tower.Event do
     }
   end
 
+  @spec from_exit(term(), Exception.stacktrace()) :: t()
+  @spec from_exit(term(), Exception.stacktrace(), Keyword.t()) :: t()
   def from_exit(reason, stacktrace, options \\ []) do
     log_event = Keyword.get(options, :log_event)
 
@@ -42,6 +46,8 @@ defmodule Tower.Event do
     }
   end
 
+  @spec from_throw(term(), Exception.stacktrace()) :: t()
+  @spec from_throw(term(), Exception.stacktrace(), Keyword.t()) :: t()
   def from_throw(reason, stacktrace, options \\ []) do
     log_event = Keyword.get(options, :log_event)
 
@@ -57,6 +63,8 @@ defmodule Tower.Event do
     }
   end
 
+  @spec from_message(:logger.level(), term()) :: t()
+  @spec from_message(:logger.level(), term(), Keyword.t()) :: t()
   def from_message(level, message, options \\ []) do
     log_event = Keyword.get(options, :log_event)
 
diff --git a/lib/tower/logger_handler.ex b/lib/tower/logger_handler.ex
index 2824b72..be38bd0 100644
--- a/lib/tower/logger_handler.ex
+++ b/lib/tower/logger_handler.ex
@@ -2,10 +2,12 @@ defmodule Tower.LoggerHandler do
   @default_log_level :critical
   @handler_id Tower
 
+  @spec attach() :: :ok | {:error, term()}
   def attach do
     :logger.add_handler(@handler_id, __MODULE__, %{level: :all})
   end
 
+  @spec detach() :: :ok | {:error, term()}
   def detach do
     :logger.remove_handler(@handler_id)
   end