diff --git a/include/patty/ax25.h b/include/patty/ax25.h
index 596f271..be6006b 100644
--- a/include/patty/ax25.h
+++ b/include/patty/ax25.h
@@ -9,8 +9,8 @@
 #include <patty/list.h>
 #include <patty/dict.h>
 
-#define PATTY_AX25_ADDR_SIZE        7
 #define PATTY_AX25_CALLSIGN_LEN     6
+#define PATTY_AX25_ADDRESS_LEN      (PATTY_AX25_CALLSIGN_LEN + 3)
 #define PATTY_AX25_IF_NAME_SIZE     8
 #define PATTY_AX25_MAX_HOPS         8
 #define PATTY_AX25_SOCK_PATH_SIZE 256
@@ -124,12 +124,10 @@ typedef struct _patty_ax25_if patty_ax25_if;
     ((c & 0x80) == 0x80)
 
 int patty_ax25_pton(const char *callsign,
-                    uint8_t ssid,
                     patty_ax25_addr *addr);
 
 int patty_ax25_ntop(const patty_ax25_addr *addr,
                     char *dest,
-                    uint8_t *ssid,
                     size_t len);
 
 void patty_ax25_addr_hash(uint32_t *hash,
diff --git a/include/patty/ax25/route.h b/include/patty/ax25/route.h
index 8d38ed6..5935e5a 100644
--- a/include/patty/ax25/route.h
+++ b/include/patty/ax25/route.h
@@ -13,14 +13,12 @@ typedef struct _patty_ax25_route {
 typedef struct _patty_dict patty_ax25_route_table;
 
 patty_ax25_route *patty_ax25_route_new(patty_ax25_if *iface,
-                                       const char *callsign,
-                                       uint8_t ssid);
+                                       const char *callsign);
 
 patty_ax25_route *patty_ax25_route_new_default(patty_ax25_if *iface);
     
 int patty_ax25_route_add_hop(patty_ax25_route *route,
-                             const char *callsign,
-                             uint8_t ssid);
+                             const char *callsign);
 
 patty_ax25_route_table *patty_ax25_route_table_new();
 
diff --git a/src/ax25.c b/src/ax25.c
index e51499e..f123537 100644
--- a/src/ax25.c
+++ b/src/ax25.c
@@ -5,30 +5,78 @@
 
 #include <patty/ax25.h>
 
+enum addr_state {
+    ADDR_NONE,
+    ADDR_CALLSIGN,
+    ADDR_SSID
+};
+
 int patty_ax25_pton(const char *callsign,
-                    uint8_t ssid,
                     patty_ax25_addr *addr) {
+    size_t len = strlen(callsign),
+           max = PATTY_AX25_CALLSIGN_LEN + 3; /* Account for SSID suffixes */
+
     int i,
-        end = 0;
+        o      = 0,
+        digits = 0;
 
-    for (i=0; i<PATTY_AX25_CALLSIGN_LEN; i++) {
-        if (callsign[i] == '\0') {
-            if (i == 0) {
-                errno = EINVAL;
+    int ssid = 0;
 
-                goto error_invalid_callsign;
-            }
+    enum addr_state state = ADDR_NONE;
 
-            end = 1;
-        } else {
-            if (!PATTY_AX25_ADDR_CHAR_VALID(callsign[i])) {
-                errno = EINVAL;
+    if (len == 0) {
+        goto error_invalid_callsign;
+    } else if (len > max) {
+        len = max;
+    }
 
-                goto error_invalid_callsign;
-            }
+    for (i=0; i<len; i++) {
+        uint8_t c = callsign[i];
+
+        switch (state) {
+            case ADDR_NONE:
+                if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z')) {
+                    state = ADDR_CALLSIGN;
+                    addr->callsign[o++] = (c & 0x7f) << 1;
+                } else {
+                    goto error_invalid_callsign;
+                }
+
+                break;
+
+            case ADDR_CALLSIGN:
+                if (o > PATTY_AX25_CALLSIGN_LEN) {
+                    goto error_invalid_callsign;
+                }
+
+                if ((c >= '0' && c <= '9') || (c >= 'A' && c <= 'Z')) {
+                    addr->callsign[o++] = (c & 0x7f) << 1;
+                } else if (c == '-') {
+                    state = ADDR_SSID;
+                } else {
+                    goto error_invalid_callsign;
+                }
+
+                break;
+
+            case ADDR_SSID:
+                if (digits >= 2) {
+                    goto error_invalid_callsign;
+                }
+
+                if (c >= '0' && c <= '9') {
+                    ssid *= 10;
+                    ssid += c - '0';
+
+                    digits++;
+                } else {
+                    goto error_invalid_callsign;
+                }
         }
+    }
 
-        addr->callsign[i] = ((end? ' ': callsign[i]) & 0x7f) << 1;
+    while (o < PATTY_AX25_CALLSIGN_LEN) {
+        addr->callsign[o++] = ' ';
     }
 
     addr->ssid = (ssid & 0x0f) << 1;
@@ -36,58 +84,85 @@ int patty_ax25_pton(const char *callsign,
     return 0;
 
 error_invalid_callsign:
+    errno = EINVAL;
+
     return -1;
 }
 
+static inline int expt(int base, int e) {
+    int ret;
+
+    if (e == 0) {
+        return 1;
+    }
+
+    ret = base;
+
+    while (--e) {
+        ret *= ret;
+    }
+
+    return ret;
+}
+
 int patty_ax25_ntop(const patty_ax25_addr *addr,
                     char *dest,
-                    uint8_t *ssid,
                     size_t len) {
-    int i, o, space = 0;
+    int i,
+        o = 0;
 
-    if (addr == NULL || dest == NULL || ssid == NULL) {
-        errno = EINVAL;
+    int ssid = (addr->ssid & 0x1e) >> 1;
 
-        goto error_invalid_args;
-    }
-
-    for (i=0, o=0; i<PATTY_AX25_CALLSIGN_LEN; i++) {
+    for (i=0; i<PATTY_AX25_CALLSIGN_LEN; i++) {
         uint8_t c;
 
         if (o == len) {
-            break;
-        }
-
-        if (PATTY_AX25_ADDR_OCTET_LAST(addr->callsign[i])) {
-            errno = EINVAL;
-
-            goto error_invalid_args;
+            goto error_overflow;
         }
 
         c = (addr->callsign[i] & 0xfe) >> 1;
 
-        if (!PATTY_AX25_ADDR_CHAR_VALID(c)) {
-            errno = EINVAL;
-
-            goto error_invalid_args;
-        } else if (c == ' ' && !space) {
-            space = 1;
-        } else if (c != ' ' && space) {
-            errno = EINVAL;
-
-            goto error_invalid_args;
+        if (c == ' ') {
+            break;
         }
 
-        dest[o++] = space? '\0': c;
+        dest[o++] = c;
+    }
+
+    if (ssid) {
+        int place = 2;
+
+        if (o == len) {
+            goto error_overflow;
+        }
+
+        dest[o++] = '-';
+
+        while (place--) {
+            int div = expt(10, place),
+                num = ssid / div;
+
+            if (num) {
+                if (o == len) {
+                    goto error_overflow;
+                }
+
+                dest[o++] = '0' + num;
+            }
+        }
+    }
+
+    if (o == len) {
+        goto error_overflow;
     }
 
     dest[o] = '\0';
 
-    *ssid = (addr->ssid & 0x1e) >> 1;
-
     return 0;
 
-error_invalid_args:
+error_overflow:
+    errno = EOVERFLOW;
+
     return -1;
 }
 
diff --git a/src/frame.c b/src/frame.c
index e532ffa..9eada96 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -38,7 +38,7 @@ static ssize_t decode_station(patty_ax25_addr *addr,
 
     memcpy(addr, ((uint8_t *)data) + offset, sizeof(*addr));
 
-    return PATTY_AX25_ADDR_SIZE;
+    return sizeof(patty_ax25_addr);
 
 error:
     return -1;
diff --git a/src/if.c b/src/if.c
index 0a3a440..68a10e9 100644
--- a/src/if.c
+++ b/src/if.c
@@ -135,10 +135,9 @@ int patty_ax25_if_addr_each(patty_ax25_if *iface,
                             int (*callback)(char *, void *), void *ctx) {
     patty_list_item *item = iface->aliases->first;
 
-    char buf[7];
-    uint8_t ssid;
+    char buf[PATTY_AX25_ADDRESS_LEN+1];
 
-    if (patty_ax25_ntop(&iface->addr, buf, &ssid, sizeof(buf)) < 0) {
+    if (patty_ax25_ntop(&iface->addr, buf, sizeof(buf)) < 0) {
         goto error_ntop_addr;
     }
 
@@ -149,7 +148,7 @@ int patty_ax25_if_addr_each(patty_ax25_if *iface,
     while (item) {
         patty_ax25_addr *addr = item->value;
 
-        if (patty_ax25_ntop(addr, buf, &ssid, sizeof(buf)) < 0) {
+        if (patty_ax25_ntop(addr, buf, sizeof(buf)) < 0) {
             goto error_ntop;
         }
 
@@ -173,10 +172,9 @@ static patty_ax25_addr *find_addr(patty_ax25_if *iface,
                                   const char *callsign) {
     patty_list_item *item = iface->aliases->first;
 
-    char buf[7];
-    uint8_t ssid;
+    char buf[PATTY_AX25_ADDRESS_LEN+1];
 
-    if (patty_ax25_ntop(&iface->addr, buf, &ssid, sizeof(buf)) < 0) {
+    if (patty_ax25_ntop(&iface->addr, buf, sizeof(buf)) < 0) {
         goto error_ntop_addr;
     }
 
@@ -187,7 +185,7 @@ static patty_ax25_addr *find_addr(patty_ax25_if *iface,
     while (item) {
         patty_ax25_addr *addr = item->value;
 
-        if (patty_ax25_ntop(addr, buf, &ssid, sizeof(buf)) < 0) {
+        if (patty_ax25_ntop(addr, buf, sizeof(buf)) < 0) {
             goto error_ntop;
         }
 
@@ -219,10 +217,12 @@ int patty_ax25_if_addr_add(patty_ax25_if *iface,
         goto error_malloc_addr;
     }
 
-    if (patty_ax25_pton(callsign, 0, addr) < 0) {
+    if (patty_ax25_pton(callsign, addr) < 0) {
         goto error_pton;
     }
 
+    addr->ssid = 0;
+
     if ((patty_list_append(iface->aliases, addr)) == NULL) {
         goto error_list_append;
     }
@@ -244,12 +244,11 @@ int patty_ax25_if_addr_delete(patty_ax25_if *iface,
     int i = 0;
 
     while (item) {
-        char buf[7];
-        uint8_t ssid;
+        char buf[PATTY_AX25_ADDRESS_LEN+1];
 
         patty_ax25_addr *addr = item->value;
 
-        if (patty_ax25_ntop(addr, buf, &ssid, sizeof(buf)) < 0) {
+        if (patty_ax25_ntop(addr, buf, sizeof(buf)) < 0) {
             goto error_ntop;
         }
 
diff --git a/src/print.c b/src/print.c
index 25314f1..0f7393c 100644
--- a/src/print.c
+++ b/src/print.c
@@ -44,19 +44,14 @@ static char *frame_cr(enum patty_ax25_frame_cr cr) {
 }
 
 static int print_addr(FILE *fh, const patty_ax25_addr *addr) {
-    char buf[7];
-    uint8_t ssid;
+    char buf[PATTY_AX25_ADDRESS_LEN];
 
-    if (patty_ax25_ntop(addr, buf, &ssid, sizeof(buf)) < 0) {
+    if (patty_ax25_ntop(addr, buf, sizeof(buf)) < 0) {
         goto error_ntop;
     }
 
     fprintf(fh, "%s", buf);
 
-    if (ssid) {
-        fprintf(fh, "-%d", (int)ssid);
-    }
-
     return 0;
 
 error_ntop:
diff --git a/src/route.c b/src/route.c
index ca09d02..d405aff 100644
--- a/src/route.c
+++ b/src/route.c
@@ -8,8 +8,7 @@
 #include <patty/ax25.h>
 
 patty_ax25_route *patty_ax25_route_new(patty_ax25_if *iface,
-                                       const char *callsign,
-                                       uint8_t ssid) {
+                                       const char *callsign) {
     patty_ax25_route *route;
 
     if ((route = malloc(sizeof(*route))) == NULL) {
@@ -19,7 +18,7 @@ patty_ax25_route *patty_ax25_route_new(patty_ax25_if *iface,
     memset(route, '\0', sizeof(*route));
 
     if (callsign) {
-        if (patty_ax25_pton(callsign, ssid, &route->dest) < 0) {
+        if (patty_ax25_pton(callsign, &route->dest) < 0) {
             goto error_pton;
         }
     }
@@ -36,19 +35,18 @@ error_malloc_route:
 }
 
 patty_ax25_route *patty_ax25_route_new_default(patty_ax25_if *iface) {
-    return patty_ax25_route_new(iface, NULL, 0);
+    return patty_ax25_route_new(iface, NULL);
 }
     
 int patty_ax25_route_add_hop(patty_ax25_route *route,
-                             const char *callsign,
-                             uint8_t ssid) {
+                             const char *callsign) {
     if (route->nhops == PATTY_AX25_MAX_HOPS) {
         errno = ENOMEM;
 
         goto error_max_hops;
     }
 
-    return patty_ax25_pton(callsign, ssid, &route->hops[route->nhops++]);
+    return patty_ax25_pton(callsign, &route->hops[route->nhops++]);
 
 error_max_hops:
     return -1;