diff --git a/include/sta/assert.hpp b/include/sta/assert.hpp
new file mode 100644
index 0000000..e40ad0c
--- /dev/null
+++ b/include/sta/assert.hpp
@@ -0,0 +1,95 @@
+/**
+ * @brief Assertion handling.
+ *
+ * Define `STA_ASSERT_ENABLE` in `<sta/config.hpp>` to enable.
+ *
+ * Defining `DEBUG` will automatically enable the module.
+ * Defining `NDEBUG` will always force module to be disabled.
+ *
+ * Both `assert_failed` and `assert_halt` provide weak definitions and
+ * can be overridden by the application. `assert_halt` is only called
+ * via the STA_HALT macro which can also be provided by the application.
+ *
+ * The default implementation of `assert_failed` uses `STA_DEBUG_PRINT` internally
+ * and will not generate any output if `<sta/debug_serial.hpp> is disabled.
+ */
+#ifndef STA_ASSERT_HPP
+#define STA_ASSERT_HPP
+
+#include <sta/config.hpp>
+
+#ifdef DEBUG
+#  ifndef STA_ASSERT_ENABLE
+#    define STA_ASSERT_ENABLE
+#  endif // !STA_ASSERT_ENABLE
+#endif // DEBUG
+
+#ifdef NDEBUG
+#  ifdef STA_ASSERT_ENABLE
+#    undef STA_ASSERT_ENABLE
+#  endif // STA_ASSERT_ENABLE
+#endif // NDEBUG
+
+
+#ifdef STA_ASSERT_ENABLE
+
+#include <cstdint>
+#include <assert.h>
+
+
+namespace sta
+{
+	/**
+	 * @brief Handle failed assertions.
+	 *
+	 * @param expr  Asserted expression or message
+	 * @param file  File name
+	 * @param line  Line number
+	 */
+	void assert_failed(const char * expr, const char * file, uint32_t line);
+	/**
+	 * @brief Stop execution.
+	 */
+	void assert_halt();
+} // namespace sta
+
+
+// Use assert_halt if STA_HALT is not defined
+#  ifndef STA_HALT
+#    define STA_HALT() sta::assert_halt()
+#  endif // !STA_HALT
+
+
+/**
+ * @brief Assert expression.
+ *
+ * @param expr  Expression
+ */
+#  define STA_ASSERT(expr)              ((void)(!(expr) && (sta::assert_failed(#expr, __FILE__, __LINE__), 1) && (STA_HALT(), 1)))
+/**
+ * @brief Assert expression.
+ *
+ * @param expr  Expression
+ * @param msg   Message shown on failure
+ */
+#  define STA_ASSERT_MSG(expr, msg)     ((void)(!(expr) && (sta::assert_failed(msg, __FILE__, __LINE__), 1) && (STA_HALT(), 1)))
+
+#else // !STA_ASSERT_ENABLE
+
+/**
+ * @brief Assert expression.
+ *
+ * @param expr  Expression
+ */
+#  define STA_ASSERT(expr, msg)         ((void)0)
+/**
+ * @brief Assert expression.
+ *
+ * @param expr  Expression
+ * @param msg   Message shown on failure
+ */
+#  define STA_ASSERT_MSG(expr, msg)     ((void)0)
+
+#endif // !STA_ASSERT_ENABLE
+
+#endif // STA_ASSERT_HPP
diff --git a/src/assert.cpp b/src/assert.cpp
new file mode 100644
index 0000000..c7e5805
--- /dev/null
+++ b/src/assert.cpp
@@ -0,0 +1,29 @@
+#include <sta/assert.hpp>
+#ifdef STA_ASSERT_ENABLE
+
+#include <sta/debug_serial.hpp>
+#include <sta/lang.hpp>
+
+
+namespace sta
+{
+	STA_WEAK
+	void assert_failed(const char * expr, const char * file, uint32_t line)
+	{
+		// printf("%s:%d: Assertion failed: %s", file, line, expr)
+		STA_DEBUG_PRINT(file);
+		STA_DEBUG_PRINT(':');
+		STA_DEBUG_PRINT(line);
+		STA_DEBUG_PRINT(": Assertion failed: ");
+		STA_DEBUG_PRINTLN(expr);
+	}
+
+	STA_WEAK
+	void assert_halt()
+	{
+		while (true);
+	}
+} // namespace sta
+
+
+#endif // STA_ASSERT_ENABLE