diff --git a/channels/chan_dahdi.c b/channels/chan_dahdi.c
index 23494e0162..2a92c8eb8c 100644
--- a/channels/chan_dahdi.c
+++ b/channels/chan_dahdi.c
@@ -9590,45 +9590,59 @@ static int my_dahdi_write(struct dahdi_pvt *p, unsigned char *buf, int len, int
 
 static int dahdi_write(struct ast_channel *ast, struct ast_frame *frame)
 {
-	struct dahdi_pvt *p = ast_channel_tech_pvt(ast);
+	struct dahdi_pvt *p;
 	int res;
 	int idx;
-	idx = dahdi_get_index(ast, p, 0);
-	if (idx < 0) {
-		ast_log(LOG_WARNING, "%s doesn't really exist?\n", ast_channel_name(ast));
-		return -1;
-	}
 
 	/* Write a frame of (presumably voice) data */
 	if (frame->frametype != AST_FRAME_VOICE) {
-		if (frame->frametype != AST_FRAME_IMAGE)
-			ast_log(LOG_WARNING, "Don't know what to do with frame type '%u'\n", frame->frametype);
+		if (frame->frametype != AST_FRAME_IMAGE) {
+			ast_log(LOG_WARNING, "Don't know what to do with frame type '%u'\n",
+				frame->frametype);
+		}
 		return 0;
 	}
 	if ((frame->subclass.format.id != AST_FORMAT_SLINEAR) &&
 		(frame->subclass.format.id != AST_FORMAT_ULAW) &&
 		(frame->subclass.format.id != AST_FORMAT_ALAW)) {
-		ast_log(LOG_WARNING, "Cannot handle frames in %s format\n", ast_getformatname(&frame->subclass.format));
+		ast_log(LOG_WARNING, "Cannot handle frames in %s format\n",
+			ast_getformatname(&frame->subclass.format));
 		return -1;
 	}
+
+	/* Return if it's not valid data */
+	if (!frame->data.ptr || !frame->datalen) {
+		return 0;
+	}
+
+	p = ast_channel_tech_pvt(ast);
+	ast_mutex_lock(&p->lock);
+
+	idx = dahdi_get_index(ast, p, 0);
+	if (idx < 0) {
+		ast_mutex_unlock(&p->lock);
+		ast_log(LOG_WARNING, "%s doesn't really exist?\n", ast_channel_name(ast));
+		return -1;
+	}
+
 	if (p->dialing) {
+		ast_mutex_unlock(&p->lock);
 		ast_debug(5, "Dropping frame since I'm still dialing on %s...\n",
 			ast_channel_name(ast));
 		return 0;
 	}
 	if (!p->owner) {
+		ast_mutex_unlock(&p->lock);
 		ast_debug(5, "Dropping frame since there is no active owner on %s...\n",
 			ast_channel_name(ast));
 		return 0;
 	}
 	if (p->cidspill) {
+		ast_mutex_unlock(&p->lock);
 		ast_debug(5, "Dropping frame since I've still got a callerid spill on %s...\n",
 			ast_channel_name(ast));
 		return 0;
 	}
-	/* Return if it's not valid data */
-	if (!frame->data.ptr || !frame->datalen)
-		return 0;
 
 	if (frame->subclass.format.id == AST_FORMAT_SLINEAR) {
 		if (!p->subs[idx].linear) {
@@ -9648,6 +9662,7 @@ static int dahdi_write(struct ast_channel *ast, struct ast_frame *frame)
 		}
 		res = my_dahdi_write(p, (unsigned char *)frame->data.ptr, frame->datalen, idx, 0);
 	}
+	ast_mutex_unlock(&p->lock);
 	if (res < 0) {
 		ast_log(LOG_WARNING, "write failed: %s\n", strerror(errno));
 		return -1;