diff --git a/include/sta/signal.hpp b/include/sta/signal.hpp
new file mode 100644
index 0000000..e32a204
--- /dev/null
+++ b/include/sta/signal.hpp
@@ -0,0 +1,37 @@
+#ifndef STA_SIGNAL_HPP
+#define STA_SIGNAL_HPP
+
+
+namespace sta
+{
+	/**
+	 * @brief Signal interface
+	 */
+	class Signal
+	{
+	public:
+		/**
+		 * @brief Enter signaled state.
+		 */
+		virtual void notify() = 0;
+		/**
+		 * @brief Check signal state w/o changing it.
+		 *
+		 * @return True if in signaled state
+		 */
+		virtual bool peek() = 0;
+		/**
+		 * @brief Check signal state.
+		 *
+		 * @return True if in signaled state
+		 */
+		virtual bool test() = 0;
+		/**
+		 * @brief Wait until signaled state is entered.
+		 */
+		virtual void wait() = 0;
+	};
+} // namespace sta
+
+
+#endif // STA_SIGNAL_HPP