diff --git a/core/error.c b/core/error.c
index e749b9f..3e7613b 100644
--- a/core/error.c
+++ b/core/error.c
@@ -719,10 +719,25 @@ static const struct b_error_definition builtin_errors[] = {
 		"Class initialisation failure"),
 };
 
+static const struct b_error_msg builtin_msg[] = {
+	B_ERROR_MSG(B_MSG_TYPE_REGISTRATION_FAILURE, "Type registration failed"),
+	B_ERROR_MSG(B_MSG_CLASS_INIT_FAILURE, "Class initialisation failed"),
+	B_ERROR_MSG_TEMPLATE(
+		B_MSG_CLASS_SPECIFIES_UNKNOWN_INTERFACE,
+		"Class @[class_name] specifies an implementation for interface "
+                "@[interface_name] that it does not extend or inherit",
+		B_ERROR_TEMPLATE_PARAM(
+			"class_name", B_ERROR_TEMPLATE_PARAM_STRING, "%s"),
+		B_ERROR_TEMPLATE_PARAM(
+			"interface_name", B_ERROR_TEMPLATE_PARAM_STRING, "%s")),
+};
+
 static const struct b_error_vendor builtin_vendor = {
 	.v_name = "Blue",
 	.v_error_definitions = builtin_errors,
 	.v_error_definitions_length = sizeof builtin_errors,
+	.v_msg = builtin_msg,
+	.v_msg_length = sizeof builtin_msg,
 };
 
 static void get_error_id(
diff --git a/core/include/blue/core/macros.h b/core/include/blue/core/macros.h
index 15816db..380836c 100644
--- a/core/include/blue/core/macros.h
+++ b/core/include/blue/core/macros.h
@@ -20,7 +20,14 @@
 #define B_TYPE_CLASS_INTERFACE_BEGIN(interface_name, interface_id)             \
 	interface_name##_class *__B_IFACE_I1(iface, __LINE__)                  \
 		= b_class_get_interface(p, interface_id);                      \
-	if (__B_IFACE_I1(iface, __LINE__)) {                                   \
+	if (!__B_IFACE_I1(iface, __LINE__)) {                                  \
+		b_throw_error_with_msg_template(                               \
+			B_ERRORS_BUILTIN, B_ERR_CLASS_INIT_FAILURE,            \
+			B_MSG_CLASS_SPECIFIES_UNKNOWN_INTERFACE,               \
+			B_ERROR_PARAM("class_name", b_class_get_name(p)),      \
+			B_ERROR_PARAM("interface_name", #interface_name));     \
+		exit(-1);                                                      \
+	} else {                                                               \
 		interface_name##_class *iface = __B_IFACE_I1(iface, __LINE__);
 #define B_TYPE_CLASS_INTERFACE_END(interface_name, interface_id) }
 #define B_INTERFACE_ENTRY(slot)                                  iface->slot
diff --git a/core/include/blue/core/status.h b/core/include/blue/core/status.h
index 2629d2a..fc1175f 100644
--- a/core/include/blue/core/status.h
+++ b/core/include/blue/core/status.h
@@ -39,6 +39,7 @@ typedef enum b_status_msg {
 	/* blue-object specific messages */
 	B_MSG_TYPE_REGISTRATION_FAILURE,
 	B_MSG_CLASS_INIT_FAILURE,
+	B_MSG_CLASS_SPECIFIES_UNKNOWN_INTERFACE,
 } b_status_msg;
 
 BLUE_API const char *b_status_to_string(b_status status);