diff --git a/src/libcharon/plugins/tnc_imc/tnc_imc.c b/src/libcharon/plugins/tnc_imc/tnc_imc.c
index 29f34d939..7c1b7b5b2 100644
--- a/src/libcharon/plugins/tnc_imc/tnc_imc.c
+++ b/src/libcharon/plugins/tnc_imc/tnc_imc.c
@@ -22,6 +22,9 @@
 
 typedef struct private_tnc_imc_t private_tnc_imc_t;
 
+/**
+ * Private data of an imv_t object.
+ */
 struct private_tnc_imc_t {
 
 	/**
@@ -72,8 +75,11 @@ METHOD(imc_t, set_message_types, void,
 	private_tnc_imc_t *this, TNC_MessageTypeList supported_types,
 							 TNC_UInt32 type_count)
 {
+	/* Free an existing MessageType list */
 	free(this->supported_types);
 	this->supported_types = NULL;
+
+	/* Store the new MessageType list */
 	this->type_count = type_count;
 	if (type_count && supported_types)
 	{
diff --git a/src/libcharon/plugins/tnc_imc/tnc_imc_manager.c b/src/libcharon/plugins/tnc_imc/tnc_imc_manager.c
index 8e0564446..f1d0f2101 100644
--- a/src/libcharon/plugins/tnc_imc/tnc_imc_manager.c
+++ b/src/libcharon/plugins/tnc_imc/tnc_imc_manager.c
@@ -24,6 +24,9 @@
 
 typedef struct private_tnc_imc_manager_t private_tnc_imc_manager_t;
 
+/**
+ * Private data of an imc_manager_t object.
+ */
 struct private_tnc_imc_manager_t {
 
 	/**
diff --git a/src/libcharon/plugins/tnc_imv/tnc_imv.c b/src/libcharon/plugins/tnc_imv/tnc_imv.c
index 3dfc50b4f..2eca072bb 100644
--- a/src/libcharon/plugins/tnc_imv/tnc_imv.c
+++ b/src/libcharon/plugins/tnc_imv/tnc_imv.c
@@ -22,6 +22,9 @@
 
 typedef struct private_tnc_imv_t private_tnc_imv_t;
 
+/**
+ * Private data of an imv_t object.
+ */
 struct private_tnc_imv_t {
 
 	/**
@@ -72,8 +75,11 @@ METHOD(imv_t, set_message_types, void,
 	private_tnc_imv_t *this, TNC_MessageTypeList supported_types,
 							 TNC_UInt32 type_count)
 {
+	/* Free an existing MessageType list */
 	free(this->supported_types);
 	this->supported_types = NULL;
+
+	/* Store the new MessageType list */
 	this->type_count = type_count;
 	if (type_count && supported_types)
 	{
diff --git a/src/libcharon/plugins/tnc_imv/tnc_imv_manager.c b/src/libcharon/plugins/tnc_imv/tnc_imv_manager.c
index fa6d35d41..08bc09392 100644
--- a/src/libcharon/plugins/tnc_imv/tnc_imv_manager.c
+++ b/src/libcharon/plugins/tnc_imv/tnc_imv_manager.c
@@ -24,6 +24,9 @@
 
 typedef struct private_tnc_imv_manager_t private_tnc_imv_manager_t;
 
+/**
+ * Private data of an imv_manager_t object.
+ */
 struct private_tnc_imv_manager_t {
 
 	/**