--- a/libtac/include/libtac.h
+++ b/libtac/include/libtac.h
@@ -66,6 +66,8 @@ extern int logmsg __P((int, const char*,
 typedef unsigned int u_int32_t;
 #endif
 
+#define TAC_PLUS_ATTRIB_MAX_LEN 255
+
 struct tac_attrib {
     char *attr;
     u_char attr_len;
--- a/libtac/lib/attrib.c
+++ b/libtac/lib/attrib.c
@@ -29,24 +29,34 @@ void tac_add_attrib(struct tac_attrib **
 
 void tac_add_attrib_pair(struct tac_attrib **attr, char *name, char sep, char *value) {
     struct tac_attrib *a;
-    u_char l1 = (u_char) strlen(name);
-    u_char l2;
+    size_t l1 = strlen(name);
+    size_t l2;
     int total_len;
-    
+
+    if (l1 > TAC_PLUS_ATTRIB_MAX_LEN-1) { /* take sep into account */
+        TACSYSLOG((LOG_WARNING,\
+            "%s: attribute `%s' exceeds max. %d characters, skipping",\
+            __FUNCTION__, name, TAC_PLUS_ATTRIB_MAX_LEN-1))
+        return;
+    }
+
+    total_len = l1 + 1; /* "name" + "sep" */
+
     if (value == NULL) {
         l2 = 0;
     } else {
-        l2 = (u_char) strlen(value);
+        l2 = strlen(value);
     }
-    total_len = l1 + l2 + 1; /* "name" + "=" + "value" */
 
-    if (total_len > 255) {
+    if (l2 > TAC_PLUS_ATTRIB_MAX_LEN-total_len) {
         TACSYSLOG((LOG_WARNING,\
-            "%s: attribute `%s' total length exceeds 255 characters, skipping",\
-            __FUNCTION__, name))
+            "%s: attribute `%s' total length exceeds %d characters, skipping",\
+            __FUNCTION__, name, TAC_PLUS_ATTRIB_MAX_LEN))
         return;
     }
-    
+
+    total_len += l2;
+
     /* initialize the list if application passed us a null pointer */
     if(*attr == NULL) {
         *attr = (struct tac_attrib *) xcalloc(1, sizeof(struct tac_attrib));