diff --git a/src/canmap.c b/src/canmap.c
index fa46159..cb676b8 100644
--- a/src/canmap.c
+++ b/src/canmap.c
@@ -129,6 +129,7 @@ int canmap_compute_frame(int *socket, struct can_frame *frame) {
             }
             else {
                 /* no free buffer */
+                printf("fatal: no free buffer available");
                 return CANMAP_COMPRET_ERROR;
             }
         case CANMAP_STATUS_FF:
@@ -147,12 +148,14 @@ int canmap_compute_frame(int *socket, struct can_frame *frame) {
                 dst->data_iter = 5;
                 dst->block_counter = 1;
                 if(write(*socket, &flowcontrol, sizeof(struct can_frame)) < 1) {
+                    printf("fatal: cannot send flowcontrol frame");
                     return CANMAP_COMPRET_ERROR;
                 }
                 return CANMAP_COMPRET_TRANS;
             }
             else {
                 /* no free buffer */
+                printf("fatal: no free buffer available");
                 return CANMAP_COMPRET_ERROR;
             }
         case CANMAP_STATUS_CF:
@@ -179,6 +182,7 @@ int canmap_compute_frame(int *socket, struct can_frame *frame) {
                     dst->block_counter = 0;
                     /* send flowcontrol */
                     if(write(*socket, &flowcontrol, sizeof(struct can_frame)) < 1) {
+                        printf("fatal: cannot send flowcontrol frame");
                         return CANMAP_COMPRET_ERROR;
                     }
                 }
@@ -186,10 +190,12 @@ int canmap_compute_frame(int *socket, struct can_frame *frame) {
             }
             else {
                 /* no buffer found */
+                printf("fatal: no buffer found for consecutive frame");
                 return CANMAP_COMPRET_ERROR;
             }
     }
     /* if the code comes till here, something is very broken */
+    printf("fatal: frame cannot be processed as canmap frame");
     return CANMAP_COMPRET_ERROR;
 }
 
diff --git a/src/canmap.h b/src/canmap.h
index 3b6a91b..7354381 100644
--- a/src/canmap.h
+++ b/src/canmap.h
@@ -52,7 +52,7 @@ THE SOFTWARE.
 
 #define CANMAP_COMPRET_COMPLETE   1       /* Transmission Complete */
 #define CANMAP_COMPRET_TRANS      0       /* Transmission pending... */
-#define CANMAP_COMPRET_ERROR      -1      /* No ISO-TP Frame or no fre buffer */
+#define CANMAP_COMPRET_ERROR      -1      /* No ISO-TP Frame or no free buffer */
 
 #define CANMAP_FLOWSTAT_CLEAR     0
 #define CANMAP_FLOWSTAT_WAIT      1
diff --git a/src/main.c b/src/main.c
index 166fc18..e2d6f64 100644
--- a/src/main.c
+++ b/src/main.c
@@ -324,15 +324,23 @@ void *can2tcp(void *arg) {
     conn = (struct connection_data*)arg;
     while(1) {
         /* if websocket is free */
-        nbytes = recv(cansocket, &frame, sizeof(struct can_frame), MSG_PEEK);
-        pthread_mutex_lock(&(conn->canlock));
         nbytes = recv(cansocket, &frame, sizeof(struct can_frame), 0);
-        if (nbytes == sizeof(struct can_frame)) {
+        if (nbytes > 0) {
+            if (verbose > 0) {
+                printf("can in: 0x%02x (%d)", frame.can_id, frame.len);
+            }
+            pthread_mutex_lock(&(conn->canlock));
             int status;
             status = canmap_compute_frame(&(cansocket), &frame);
             if(status == CANMAP_COMPRET_COMPLETE) {
                 if(canmap_get_frame(&isoframe)) {
+                    if (verbose > 0) {
+                        printf("canmap complete: 0x%02x->0x%02x (%04d)", isoframe.sender, isoframe.rec, isoframe.dl);
+                    }
                     memset(sock_send, 0, sizeof(sock_send));
+                    if (verbose > 0) {
+                        printf("tcp out: %s", sock_send);
+                    }
                     canmap_fr2str(sock_send, &isoframe);
                     send(conn->websocket, sock_send, strlen(sock_send), 0);
                     canmap_reset_frame(&isoframe);
@@ -341,8 +349,8 @@ void *can2tcp(void *arg) {
             else if(status == CANMAP_COMPRET_ERROR) {
                 /* msg still in transmission */
             }
+            pthread_mutex_unlock(&(conn->canlock));
         }
-        pthread_mutex_unlock(&(conn->canlock));
     }
 }