diff --git a/src/runtime_warning.hpp b/src/runtime_warning.hpp
new file mode 100644
index 0000000..78db37c
--- /dev/null
+++ b/src/runtime_warning.hpp
@@ -0,0 +1,45 @@
+#pragma once
+
+#include <exception>
+#include <string>
+
+namespace phosphor::software::updater
+{
+
+/**
+ * @class RuntimeWarning
+ *
+ * Exception class to report a runtime warning condition.
+ */
+class RuntimeWarning : public std::exception
+{
+  public:
+    // Specify which compiler-generated methods we want
+    RuntimeWarning() = delete;
+    RuntimeWarning(const RuntimeWarning&) = default;
+    RuntimeWarning(RuntimeWarning&&) = default;
+    RuntimeWarning& operator=(const RuntimeWarning&) = default;
+    RuntimeWarning& operator=(RuntimeWarning&&) = default;
+    ~RuntimeWarning() override = default;
+
+    /** @brief Constructor.
+     *
+     * @param error error message
+     */
+    explicit RuntimeWarning(const std::string& error) : error{error} {}
+
+    /** @brief Returns the description of this error.
+     *
+     * @return error description
+     */
+    const char* what() const noexcept override
+    {
+        return error.c_str();
+    }
+
+  private:
+    /** @brief Error message */
+    std::string error;
+};
+
+} // namespace phosphor::software::updater