diff --git a/Changes b/Changes
index 9ceb4e40b..7da224c26 100644
--- a/Changes
+++ b/Changes
@@ -18,6 +18,7 @@ Provided by illu. <illu@rs2i.net> - 2006
 01/25 F Updated the french language file.                                 [ #00]
 
 Provided by Trystan <trystan@nomadirc.net> - 2006
+02/23 F Usermatching possible null arg on sstrdup.                        [ #00]
 02/12 F Double unbanning of in certain conditions.                        [ #00]
 01/25 F va_copy issue for various platforms.                              [ #00]
 
diff --git a/src/users.c b/src/users.c
index d62fba853..c8abab7c3 100644
--- a/src/users.c
+++ b/src/users.c
@@ -977,10 +977,16 @@ int is_excepted_mask(ChannelInfo * ci, char *mask)
 
 int match_usermask(const char *mask, User * user)
 {
-    char *mask2 = sstrdup(mask);
+    char *mask2;
     char *nick, *username, *host;
     int result;
 
+    if (!mask || !*mask) {
+        return 0;
+    }
+
+    mask2 = sstrdup(mask);
+
     if (strchr(mask2, '!')) {
         nick = strtok(mask2, "!");
         username = strtok(NULL, "@");
@@ -1016,10 +1022,16 @@ int match_usermask(const char *mask, User * user)
 
 int match_userip(const char *mask, User * user, char *iphost)
 {
-    char *mask2 = sstrdup(mask);
+    char *mask2;
     char *nick, *username, *host;
     int result;
 
+    if (!mask || !*mask) {
+        return 0;
+    }
+
+    mask2 = sstrdup(mask);
+
     if (strchr(mask2, '!')) {
         nick = strtok(mask2, "!");
         username = strtok(NULL, "@");