diff --git a/src/brei-shared.c b/src/brei-shared.c
index 9325619..10aad0c 100644
--- a/src/brei-shared.c
+++ b/src/brei-shared.c
@@ -31,6 +31,73 @@
 
 #include "brei-shared.h"
 
+struct brei_context {
+	struct object object;
+	void *parent_context;
+
+	brei_logfunc_t log_func;
+	void *log_context;
+};
+
+static void
+brei_context_destroy(struct brei_context *ctx)
+{
+}
+
+static
+OBJECT_IMPLEMENT_CREATE(brei_context);
+OBJECT_IMPLEMENT_REF(brei_context);
+OBJECT_IMPLEMENT_UNREF_CLEANUP(brei_context);
+OBJECT_IMPLEMENT_SETTER(brei_context, log_func, brei_logfunc_t);
+OBJECT_IMPLEMENT_SETTER(brei_context, log_context, void *);
+
+struct brei_context *
+brei_context_new(void *parent_context)
+{
+	struct brei_context *brei = brei_context_create(NULL);
+
+	brei->parent_context = parent_context;
+
+	return brei;
+}
+
+#define log_debug(T_, ...) \
+	brei_log_msg((T_), BREI_LOG_PRIORITY_DEBUG, __FILE__, __LINE__, __func__, __VA_ARGS__)
+#define log_info(T_, ...) \
+	brei_log_msg((T_), BREI_LOG_PRIORITY_INFO, __FILE__, __LINE__, __func__, __VA_ARGS__)
+#define log_warn(T_, ...) \
+	brei_log_msg((T_), BREI_LOG_PRIORITY_WARNING, __FILE__, __LINE__, __func__, __VA_ARGS__)
+#define log_error(T_, ...) \
+	brei_log_msg((T_), BREI_LOG_PRIORITY_ERROR, __FILE__, __LINE__, __func__, __VA_ARGS__)
+#define log_bug(T_, ...) \
+	brei_log_msg((T_), BREI_LOG_PRIORITY_ERROR, __FILE__, __LINE__, __func__, "🪳  brei bug:  " __VA_ARGS__)
+#define log_bug_client(T_, ...) \
+	brei_log_msg((T_), BREI_LOG_PRIORITY_ERROR, __FILE__, __LINE__, __func__, "🪲  Bug: " __VA_ARGS__)
+
+_printf_(6, 0) static void
+brei_log_msg_va(struct brei_context *brei,
+	      enum brei_log_priority priority,
+	      const char *file, int lineno, const char *func,
+	      const char *format,
+	      va_list ap)
+{
+	if (brei->log_func && brei->log_context)
+		brei->log_func(brei->log_context, priority, file, lineno, func, format, ap);
+}
+
+
+_printf_(6, 7) static void
+brei_log_msg(struct brei_context *brei,
+	     enum brei_log_priority priority,
+	     const char *file, int lineno, const char *func,
+	     const char *format, ...)
+{
+	va_list args;
+	va_start(args, format);
+	brei_log_msg_va(brei, priority, file, lineno, func, format, args);
+	va_end(args);
+}
+
 /**
  * Return the number of int32s required to store count bytes.
  */
@@ -41,11 +108,13 @@ bytes_to_int32(uint32_t count)
 }
 
 static int
-brei_demarshal(struct iobuf *buf, const char *signature, union brei_arg **args_out)
+brei_demarshal(struct brei_context *brei, struct iobuf *buf, const char *signature, union brei_arg **args_out)
 {
 	size_t nargs = strlen(signature);
-	if (nargs > 256)
+	if (nargs > 256) {
+		log_bug(brei, "Too many arguments in signature (%zu)", nargs);
 		return -EPROTO;
+	}
 
 	/* This over-allocates if we have more than one char per type but meh */
 	_cleanup_free_ union brei_arg *args = xalloc(nargs * sizeof(*args));
@@ -77,19 +146,25 @@ brei_demarshal(struct iobuf *buf, const char *signature, union brei_arg **args_o
 
 			uint32_t slen32 = bytes_to_int32(slen);
 			if (end - p < slen32) {
+				log_bug_client(brei, "Invalid string length %zu, only %li bytes remaining", slen, (end - p) * 4);
 				return -EINVAL;
 			}
 
 			const char *str = (char*)p;
 
 			/* strings must be null-terminated */
-			if (slen && str[slen - 1] != '\0')
+			if (slen && str[slen - 1] != '\0') {
+				log_bug_client(brei, "Message string not zero-terminated");
 				return -EINVAL;
+			}
 
 			arg->str = str;
 			p += slen32;
 			break;
 			}
+		default:
+			log_bug(brei, "Invalid signature '%c'", *s);
+			return -EBADMSG;
 		}
 		arg++;
 		s++;
@@ -102,7 +177,7 @@ brei_demarshal(struct iobuf *buf, const char *signature, union brei_arg **args_o
 }
 
 static int
-brei_marshal(struct iobuf *buf, const char *signature, size_t nargs, va_list args)
+brei_marshal(struct brei_context *brei, struct iobuf *buf, const char *signature, size_t nargs, va_list args)
 {
 	const char *s = signature;
 	int32_t i;
@@ -144,6 +219,9 @@ brei_marshal(struct iobuf *buf, const char *signature, size_t nargs, va_list arg
 			}
 			break;
 		}
+		default:
+			log_bug(brei, "Invalid signature '%c'", *s);
+			return -EBADMSG;
 		}
 		s++;
 	}
@@ -152,7 +230,8 @@ brei_marshal(struct iobuf *buf, const char *signature, size_t nargs, va_list arg
 }
 
 int
-brei_send_message(int fd,
+brei_send_message(struct brei_context *brei,
+		  int fd,
 		  uint32_t id,
 		  uint32_t opcode,
 		  const char *signature,
@@ -166,7 +245,7 @@ brei_send_message(int fd,
 	iobuf_append(buf, (const char *)&id, 4);
 	iobuf_append(buf, (const char *)&opcode, 4);
 
-	int rc = brei_marshal(buf, signature, nargs, args);
+	int rc = brei_marshal(brei, buf, signature, nargs, args);
 
 	if (rc == 0) {
 		/* now write the actual message length, including header */
@@ -178,7 +257,8 @@ brei_send_message(int fd,
 }
 
 int
-brei_dispatch(int fd,
+brei_dispatch(struct brei_context *brei,
+	      int fd,
 	      int (*lookup_object)(uint32_t object_id, struct brei_object **object, void *user_data),
 	      void *user_data)
 {
@@ -222,6 +302,8 @@ brei_dispatch(int fd,
 		assert(interface);
 
 		if (opcode >= interface->nincoming) {
+			log_bug_client(brei, "opcode %u exceeds interface %s method count %u",
+				       opcode, interface->name, interface->nincoming);
 			rc = -EINVAL;
 			goto error;
 		}
@@ -231,17 +313,21 @@ brei_dispatch(int fd,
 		/* Demarshal the protocol into a set of arguments */
 		_cleanup_free_ union brei_arg * args = NULL;
 		const char *signature = interface->incoming[opcode].signature;
-		int nargs = brei_demarshal(buf, signature, &args);
+		int nargs = brei_demarshal(brei, buf, signature, &args);
 		if (nargs < 0) {
 			rc = nargs;
 			goto error;
 		}
 
+		log_debug(brei, "dispatching %s.%s() on object %#x", interface->name, interface->incoming[opcode].name, object_id);
+
 		/* Success! Let's pass this on to the
 		 * context to process */
 		rc = interface->dispatcher(object->implementation, opcode, nargs, args);
-		if (rc < 0)
+		if (rc < 0) {
+			log_error(brei, "dispatch failed with %d (%s)", -rc, strerror(-rc));
 			goto error;
+		}
 
 		iobuf_pop(buf, msglen - headersize);
 	}
@@ -266,26 +352,27 @@ brei_drain_fd(int fd)
 #include "util-munit.h"
 
 static int
-brei_marshal_va(struct iobuf *buf, const char *signature, size_t nargs, ...)
+brei_marshal_va(struct brei_context *brei, struct iobuf *buf, const char *signature, size_t nargs, ...)
 {
 	va_list args;
 
 	va_start(args, nargs);
-	int rc = brei_marshal(buf, signature, nargs, args);
+	int rc = brei_marshal(brei, buf, signature, nargs, args);
 	va_end(args);
 	return rc;
 }
 
 MUNIT_TEST(test_brei_marshal)
 {
+	_unref_(brei_context) *brei = brei_context_new(NULL);
 	_cleanup_iobuf_ struct iobuf *buf = iobuf_new(64);
 	const char *str = "eierspeise";
 
-	int rc = brei_marshal_va(buf, "noiusf", 5, 0xab, 0xcd, -13, 0xfffd, str, 1.45);
+	int rc = brei_marshal_va(brei, buf, "noiusf", 5, 0xab, 0xcd, -13, 0xfffd, str, 1.45);
 	munit_assert_int(rc, ==, 0);
 
-	_cleanup_free_ union brei_arg *args;
-	rc = brei_demarshal(buf, "noiusf", &args);
+	_cleanup_free_ union brei_arg *args = NULL;
+	rc = brei_demarshal(brei, buf, "noiusf", &args);
 	munit_assert_int(rc, ==, 6);
 
 	munit_assert_int(args[0].obj, ==, 0xab);
@@ -298,13 +385,30 @@ MUNIT_TEST(test_brei_marshal)
 	return MUNIT_OK;
 }
 
+MUNIT_TEST(test_brei_marshal_bad_sig)
+{
+	_unref_(brei_context) *brei = brei_context_new(NULL);
+	_cleanup_iobuf_ struct iobuf *buf = iobuf_new(64);
+	const char *str = "eierspeise";
+
+	int rc = brei_marshal_va(brei, buf, "noiusf", 5, 0xab, 0xcd, -13, 0xfffd, str, 1.45);
+	munit_assert_int(rc, ==, 0);
+
+	_cleanup_free_ union brei_arg *args = NULL;
+	rc = brei_demarshal(brei, buf, "nxoiusf", &args);
+	munit_assert_int(rc, ==, -EBADMSG);
+
+	return MUNIT_OK;
+}
+
 static int
 brei_send_message_va(int fd, uint32_t id, uint32_t opcode,
 		     const char *signature, size_t nargs, ...)
 {
+	_unref_(brei_context) *brei = brei_context_new(NULL);
 	va_list args;
 	va_start(args, nargs);
-	int rc = brei_send_message(fd, id, opcode, signature, nargs, args);
+	int rc = brei_send_message(brei, fd, id, opcode, signature, nargs, args);
 	va_end(args);
 	return rc;
 }
diff --git a/src/brei-shared.h b/src/brei-shared.h
index abd5072..9a59352 100644
--- a/src/brei-shared.h
+++ b/src/brei-shared.h
@@ -31,11 +31,32 @@
 #include <stdarg.h>
 
 #include "util-list.h"
+#include "util-object.h"
 
 struct brei_interface;
 struct brei_message;
 struct brei_object;
 
+struct brei_context;
+
+enum brei_log_priority {
+	BREI_LOG_PRIORITY_DEBUG = 10,
+	BREI_LOG_PRIORITY_INFO = 20,
+	BREI_LOG_PRIORITY_WARNING = 30,
+	BREI_LOG_PRIORITY_ERROR = 40,
+};
+
+typedef void (*brei_logfunc_t)(void *context, enum brei_log_priority priority,
+	    const char *file, int lineno, const char *func,
+	    const char *format, va_list args);
+
+struct brei_context *brei_context_new(void *user_data);
+
+OBJECT_DECLARE_SETTER(brei_context, log_func, brei_logfunc_t);
+OBJECT_DECLARE_SETTER(brei_context, log_context, void *);
+OBJECT_DECLARE_REF(brei_context);
+OBJECT_DECLARE_UNREF(brei_context);
+
 union brei_arg {
   uint32_t u32;
   int32_t i32;
@@ -77,7 +98,8 @@ struct brei_object {
 };
 
 int
-brei_send_message(int fd,
+brei_send_message(struct brei_context *brei,
+		  int fd,
 		  uint32_t id,
 		  uint32_t opcode,
 		  const char *signature,
@@ -95,7 +117,8 @@ brei_send_message(int fd,
  * @return zero on success or a negative errno otherwise
  */
 int
-brei_dispatch(int fd,
+brei_dispatch(struct brei_context *brei,
+	      int fd,
 	      int (*lookup_object)(uint32_t object_id, struct brei_object **object, void *user_data),
 	      void *user_data);
 
diff --git a/src/libei-private.h b/src/libei-private.h
index f633b5a..3a7ad53 100644
--- a/src/libei-private.h
+++ b/src/libei-private.h
@@ -68,6 +68,7 @@ struct ei {
 	uint32_t next_object_id;
 
 	void *user_data;
+	struct brei_context *brei;
 	struct sink *sink;
 	struct source *source;
 	struct ei_backend_interface backend_interface;
diff --git a/src/libei.c b/src/libei.c
index 41a1755..a83b5c8 100644
--- a/src/libei.c
+++ b/src/libei.c
@@ -64,6 +64,7 @@ ei_destroy(struct ei *ei)
 	ei->backend = NULL;
 	ei_connection_setup_unref(ei->connection_setup);
 	ei_connection_unref(ei->connection);
+	brei_context_unref(ei->brei);
 	sink_unref(ei->sink);
 	free(ei->name);
 }
@@ -101,6 +102,9 @@ ei_create_context(bool is_sender, void *user_data)
 
 	ei->connection_setup = ei_connection_setup_new(ei, VERSION_V(1));
 	ei->next_object_id = 1;
+	ei->brei = brei_context_new(ei);
+	brei_context_set_log_context(ei->brei, ei);
+	brei_context_set_log_func(ei->brei, (brei_logfunc_t)ei_log_msg_va);
 
 	ei_log_set_handler(ei, NULL);
 	ei_log_set_priority(ei, EI_LOG_PRIORITY_INFO);
@@ -697,7 +701,7 @@ connection_dispatch(struct source *source, void *userdata)
 	struct ei *ei = userdata;
 	enum ei_state old_state = ei->state;
 
-	int rc = brei_dispatch(source_get_fd(source), lookup_object, ei);
+	int rc = brei_dispatch(ei->brei, source_get_fd(source), lookup_object, ei);
 	if (rc < 0) {
 		brei_drain_fd(source_get_fd(source));
 		ei_disconnect(ei);
@@ -738,7 +742,7 @@ ei_send_message(struct ei *ei, const struct brei_object *object,
 
 	va_list args;
 	va_start(args, nargs);
-	int rc = brei_send_message(fd, object->id, opcode, signature, nargs, args);
+	int rc = brei_send_message(ei->brei, fd, object->id, opcode, signature, nargs, args);
 	va_end(args);
 	return rc < 0 ? rc : 0;
 }
diff --git a/src/libeis-client.c b/src/libeis-client.c
index 827332e..d263e05 100644
--- a/src/libeis-client.c
+++ b/src/libeis-client.c
@@ -53,6 +53,7 @@ eis_client_destroy(struct eis_client *client)
 	eis_connection_setup_unref(client->setup);
 	eis_connection_unref(client->connection);
 	free(client->name);
+	brei_context_unref(client->brei);
 	source_remove(client->source);
 	source_unref(client->source);
 	list_remove(&client->link);
@@ -158,7 +159,7 @@ eis_client_send_message(struct eis_client *client, const struct brei_object *obj
 
 	va_list args;
 	va_start(args, nargs);
-	int rc = brei_send_message(fd, object->id, opcode, signature, nargs, args);
+	int rc = brei_send_message(client->brei, fd, object->id, opcode, signature, nargs, args);
 	va_end(args);
 	return rc < 0 ? rc : 0;
 }
@@ -325,7 +326,7 @@ client_dispatch(struct source *source, void *userdata)
 	_unref_(eis_client) *client = eis_client_ref(userdata);
 	enum eis_client_state old_state = client->state;
 
-	int rc = brei_dispatch(source_get_fd(source), lookup_object, client);
+	int rc = brei_dispatch(client->brei, source_get_fd(source), lookup_object, client);
 	if (rc < 0) {
 		brei_drain_fd(source_get_fd(source));
 		client_disconnect(client, strerror(-rc));
@@ -358,6 +359,10 @@ eis_client_new(struct eis *eis, int fd)
 	static uint32_t client_id;
 	struct eis_client *client = eis_client_create(&eis->object);
 
+	client->brei = brei_context_new(client);
+	brei_context_set_log_context(client->brei, eis);
+	brei_context_set_log_func(client->brei, (brei_logfunc_t)eis_log_msg_va);
+
 	client->is_sender = true;
 	client->id = ++client_id;
 	list_init(&client->seats);
diff --git a/src/libeis-client.h b/src/libeis-client.h
index 62df1d3..a7890ad 100644
--- a/src/libeis-client.h
+++ b/src/libeis-client.h
@@ -50,6 +50,7 @@ struct eis_client_interface_versions {
 
 struct eis_client {
 	struct object object;
+	struct brei_context *brei;
 	struct eis_connection *connection;
 
 	struct list proto_objects; /* struct brei_objects list */