diff --git a/include/hexagram/can.h b/include/hexagram/can.h
index 1651ba6..ac97a5a 100644
--- a/include/hexagram/can.h
+++ b/include/hexagram/can.h
@@ -6,11 +6,7 @@
 #include <linux/can.h>
 #include <linux/can/raw.h>
 
-typedef struct _hexagram_can_if {
-    struct sockaddr_can addr;
-    struct ifreq ifr;
-    int sock;
-} hexagram_can_if;
+typedef struct _hexagram_can_if hexagram_can_if;
 
 hexagram_can_if *hexagram_can_if_open(const char *name);
 
@@ -22,4 +18,10 @@ int hexagram_can_if_read(hexagram_can_if *can_if,
 int hexagram_can_if_write(hexagram_can_if *can_if,
                           struct can_frame *frame);
 
+int hexagram_can_if_fd(hexagram_can_if *can_if);
+
+void hexagram_can_if_fd_set(hexagram_can_if *can_if, fd_set *fds);
+
+int hexagram_can_if_fd_isset(hexagram_can_if *can_if, fd_set *fds);
+
 #endif /* _HEXAGRAM_CAN_H */
diff --git a/src/can.c b/src/can.c
index 63685f7..57bd50c 100644
--- a/src/can.c
+++ b/src/can.c
@@ -6,6 +6,12 @@
 
 #include <hexagram/can.h>
 
+struct _hexagram_can_if {
+    struct sockaddr_can addr;
+    struct ifreq ifr;
+    int sock;
+};
+
 hexagram_can_if *hexagram_can_if_open(const char *name) {
     hexagram_can_if *can_if;
 
@@ -65,3 +71,15 @@ int hexagram_can_if_write(hexagram_can_if *can_if,
                           struct can_frame *frame) {
     return write(can_if->sock, frame, sizeof(*frame));
 }
+
+int hexagram_can_if_fd(hexagram_can_if *can_if) {
+    return can_if->sock;
+}
+
+void hexagram_can_if_fd_set(hexagram_can_if *can_if, fd_set *fds) {
+    FD_SET(can_if->sock, fds);
+}
+
+int hexagram_can_if_fd_isset(hexagram_can_if *can_if, fd_set *fds) {
+    return FD_ISSET(can_if->sock, fds);
+}
diff --git a/src/capture.c b/src/capture.c
index dde4e86..278f534 100644
--- a/src/capture.c
+++ b/src/capture.c
@@ -141,11 +141,12 @@ error_gettimeofday:
 int hexagram_capture_save(hexagram_capture *capture,
                           hexagram_can_if *can_if) {
     struct can_frame frame;
+    int sock = hexagram_can_if_fd(can_if);
 
     while (hexagram_can_if_read(can_if, &frame) > 0) {
         struct timeval timestamp;
 
-        if (ioctl(can_if->sock, SIOCGSTAMP, &timestamp) < 0) {
+        if (ioctl(sock, SIOCGSTAMP, &timestamp) < 0) {
             goto error_io;
         }
 
@@ -163,12 +164,12 @@ error_io:
 int hexagram_capture_replay(hexagram_capture *capture,
                             hexagram_can_if *can_if,
                             float speed) {
-    struct timeval timestamp;
-
     uint64_t usec_last = 0,
              usec;
 
+    struct timeval timestamp;
     struct can_frame frame;
+    int sock = hexagram_can_if_fd(can_if);
 
     while (1) {
         ssize_t len = hexagram_capture_read(capture,
@@ -188,7 +189,7 @@ int hexagram_capture_replay(hexagram_capture *capture,
             usleep(speed * (useconds_t)(usec - usec_last));
         }
 
-        if (write(can_if->sock, &frame, sizeof(struct can_frame)) < 0) {
+        if (write(sock, &frame, sizeof(struct can_frame)) < 0) {
             goto error_io;
         }