diff --git a/src/bts.cpp b/src/bts.cpp
index 72e1621..3d29ad6 100644
--- a/src/bts.cpp
+++ b/src/bts.cpp
@@ -759,7 +759,7 @@
 		} else {
 			tbf->set_ta(ta);
 			TBF_SET_STATE(tbf, GPRS_RLCMAC_FLOW);
-			tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_CCCH);
+			TBF_ASS_TYPE_SET(tbf, GPRS_RLCMAC_FLAG_CCCH);
 			T_START(tbf, T3169, m_bts.t3169, 0, "RACH (new UL-TBF)", true);
 			LOGPTBF(tbf, LOGL_DEBUG, "[UPLINK] START\n");
 			LOGPTBF(tbf, LOGL_DEBUG, "RX: [PCU <- BTS] RACH "
@@ -1042,7 +1042,7 @@
 			LOGPTBF(new_tbf, LOGL_INFO,
 				"The TBF has been confirmed on the PACCH, "
 				"changed type from CCCH to PACCH\n");
-			new_tbf->state_flags |= (1 << GPRS_RLCMAC_FLAG_PACCH);
+			TBF_ASS_TYPE_SET(new_tbf, GPRS_RLCMAC_FLAG_PACCH);
 		}
 		TBF_SET_STATE(new_tbf, GPRS_RLCMAC_FLOW);
 		/* stop pending assignment timer */
diff --git a/src/tbf.h b/src/tbf.h
index 803ea33..2ed63f9 100644
--- a/src/tbf.h
+++ b/src/tbf.h
@@ -191,6 +191,8 @@
 #define TBF_POLL_SCHED_SET(t) do { t->poll_sched_set(__FILE__, __LINE__); } while(0)
 #define TBF_POLL_SCHED_UNSET(t) do { t->poll_sched_unset(__FILE__, __LINE__); } while(0)
 #define TBF_SET_ASS_ON(t, fl, chk) do { t->set_assigned_on(fl, chk, __FILE__, __LINE__); } while(0)
+#define TBF_ASS_TYPE_SET(t, kind) do { t->ass_type_mod(kind, false, __FILE__, __LINE__); } while(0)
+#define TBF_ASS_TYPE_UNSET(t, kind) do { t->ass_type_mod(kind, true, __FILE__, __LINE__); } while(0)
 
 struct gprs_rlcmac_tbf {
 	gprs_rlcmac_tbf(BTS *bts_, gprs_rlcmac_tbf_direction dir);
@@ -213,6 +215,7 @@
 	void check_pending_ass();
 	bool check_n_clear(uint8_t state_flag);
 	void set_assigned_on(uint8_t state_flag, bool check_ccch, const char *file, int line);
+	void ass_type_mod(uint8_t t, bool unset, const char *file, int line);
 	const char *state_name() const;
 
 	const char *name() const;
@@ -422,11 +425,57 @@
 	set_state(GPRS_RLCMAC_ASSIGN, file, line);
 	if (check_ccch) {
 		if (!(state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH)))
-			state_flags |= (1 << state_flag);
+			ass_type_mod(state_flag, false, file, line);
 	} else
 		state_flags |= (1 << state_flag);
 }
 
+inline void gprs_rlcmac_tbf::ass_type_mod(uint8_t t, bool unset, const char *file, int line)
+{
+	const char *ch = "UNKNOWN";
+	switch (t) {
+	case GPRS_RLCMAC_FLAG_CCCH:
+		if (unset) {
+			if (!(state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH)))
+				return;
+		} else {
+			if (state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH))
+				LOGPSRC(DTBF, LOGL_ERROR, file, line,
+					"%s attempted to set ass. type CCCH which is already set.\n",
+					tbf_name(this));
+		}
+		ch = "CCCH";
+		break;
+	case GPRS_RLCMAC_FLAG_PACCH:
+		if (unset) {
+			if (!(state_flags & (1 << GPRS_RLCMAC_FLAG_PACCH)))
+				return;
+		} else {
+			if (state_flags & (1 << GPRS_RLCMAC_FLAG_PACCH))
+				LOGPSRC(DTBF, LOGL_ERROR, file, line,
+					"%s attempted to set ass. type PACCH which is already set.\n",
+					tbf_name(this));
+		}
+		ch = "PACCH";
+		break;
+	default:
+		LOGPSRC(DTBF, LOGL_ERROR, file, line, "%s attempted to %sset unexpected ass. type %d - FIXME!\n",
+			tbf_name(this), unset ? "un" : "", t);
+		return;
+	}
+
+	LOGPSRC(DTBF, LOGL_INFO, file, line, "%s %sset ass. type %s [prev CCCH:%u, PACCH:%u]\n",
+		tbf_name(this), unset ? "un" : "", ch,
+		state_flags & (1 << GPRS_RLCMAC_FLAG_CCCH),
+		state_flags & (1 << GPRS_RLCMAC_FLAG_PACCH));
+
+	if (unset) {
+		state_flags &= GPRS_RLCMAC_FLAG_TO_MASK; /* keep to flags */
+		state_flags &= ~(1 << t);
+	} else
+		state_flags |= (1 << t);
+}
+
 inline void gprs_rlcmac_tbf::set_state(enum gprs_rlcmac_tbf_state new_state, const char *file, int line)
 {
 	LOGPSRC(DTBF, LOGL_DEBUG, file, line, "%s changes state from %s to %s\n",
diff --git a/src/tbf_dl.cpp b/src/tbf_dl.cpp
index 0587a4a..dc4fa6a 100644
--- a/src/tbf_dl.cpp
+++ b/src/tbf_dl.cpp
@@ -1104,9 +1104,7 @@
 	m_wait_confirm = 0;
 	m_window.reset();
 
-	/* keep to flags */
-	state_flags &= GPRS_RLCMAC_FLAG_TO_MASK;
-	state_flags &= ~(1 << GPRS_RLCMAC_FLAG_CCCH);
+	TBF_ASS_TYPE_UNSET(this, GPRS_RLCMAC_FLAG_CCCH);
 
 	return 0;
 }
@@ -1132,9 +1130,7 @@
 	/* reset rlc states */
 	m_window.reset();
 
-	/* keep to flags */
-	state_flags &= GPRS_RLCMAC_FLAG_TO_MASK;
-	state_flags &= ~(1 << GPRS_RLCMAC_FLAG_CCCH);
+	TBF_ASS_TYPE_UNSET(this, GPRS_RLCMAC_FLAG_CCCH);
 
 	return 0;
 }