diff --git a/common/string_calls.c b/common/string_calls.c
index 941a2995..b039c692 100644
--- a/common/string_calls.c
+++ b/common/string_calls.c
@@ -232,7 +232,10 @@ g_get_display_string(char buff[], unsigned int bufflen)
         // Return the unqualified part of the name
         p = strrchr(str, '/');
         p = (p != NULL) ? (p + 1) : str;
-        strlcpy(buff, p, bufflen);
+        if (strlcpy(buff, p, bufflen) >= bufflen)
+        {
+            rv = -1; /* Buffer overflow */
+        }
     }
     else if ((str = g_getenv("DISPLAY")) != NULL)
     {
@@ -240,7 +243,11 @@ g_get_display_string(char buff[], unsigned int bufflen)
 
         if (n >= 0)
         {
-            g_snprintf(buff, bufflen, "X11-%d", n);
+            if ((unsigned int)g_snprintf(buff, bufflen, "X11-%d", n)
+                    >= bufflen)
+            {
+                rv = -1; /* Buffer overflow */
+            }
         }
         else
         {
diff --git a/sesman/sesexec/session.c b/sesman/sesexec/session.c
index 0231dfce..7d49b6fa 100644
--- a/sesman/sesexec/session.c
+++ b/sesman/sesexec/session.c
@@ -682,13 +682,12 @@ start_x_server(const struct login_info *login_info,
                  g_cfg->env_names,
                  g_cfg->env_values);
 
-    if (sp->type == SCP_SESSION_TYPE_XVNC)
+    /* Allocate the passwd_file if required */
+    if (sp->type == SCP_SESSION_TYPE_XVNC &&
+            (passwd_file = get_xvnc_passwd_file_name(sp->x11_display)) == NULL)
     {
-        char guid_str[GUID_STR_SIZE];
-        passwd_file = get_xvnc_passwd_file_name(sp->x11_display);
-
-        guid_to_str(&sp->guid, guid_str);
-        set_xvnc_passwd(passwd_file, guid_str);
+        /* An error has been logged */
+        return;
     }
 
     /* prepare the Xauthority stuff */
@@ -714,6 +713,7 @@ start_x_server(const struct login_info *login_info,
     {
         switch (sp->type)
         {
+                char guid_str[GUID_STR_SIZE];
                 char port[256];
 
             case SCP_SESSION_TYPE_XORG:
@@ -721,6 +721,8 @@ start_x_server(const struct login_info *login_info,
                 break;
 
             case SCP_SESSION_TYPE_XVNC:
+                guid_to_str(&sp->guid, guid_str);
+                set_xvnc_passwd(passwd_file, guid_str);
                 xserver_params = prepare_xvnc_xserver_params(sd, authfile,
                                  passwd_file, NULL);
                 break;
diff --git a/sesman/tools/dis.c b/sesman/tools/dis.c
index 76c2e0ad..9207131b 100644
--- a/sesman/tools/dis.c
+++ b/sesman/tools/dis.c
@@ -49,7 +49,7 @@ int main(int argc, char **argv)
 
     if (g_get_display_string(disstr, sizeof(disstr)) < 0)
     {
-        printf("Can't find teh display from the environment\n");
+        printf("Can't find the display from the environment\n");
         return 1;
     }
 
diff --git a/xrdp/xrdp_mm.c b/xrdp/xrdp_mm.c
index f1a76380..08570218 100644
--- a/xrdp/xrdp_mm.c
+++ b/xrdp/xrdp_mm.c
@@ -2963,7 +2963,7 @@ cleanup_states(struct xrdp_mm *self)
  */
 
 static int
-parse_chansrvport(const char *value, char *dest, int dest_size, int uid)
+parse_chansrvport(const char *value, char dest[], int dest_size, int uid)
 {
     int rv = 0;
     char dstr[MAX_DISPLAY_NAME_SIZE];
@@ -3003,8 +3003,14 @@ parse_chansrvport(const char *value, char *dest, int dest_size, int uid)
         {
             // X11 compatibility
             int dnum = g_atoi(dstr);
-            (void)g_get_display_string_from_x11_display(
-                dnum, dstr, sizeof(dstr));
+            if (g_get_display_string_from_x11_display(
+                        dnum, dstr, sizeof(dstr)) < 0)
+            {
+                LOG(LOG_LEVEL_WARNING,
+                    "Ignoring chansrvport string "
+                    "with bad X11 display number '%s'", value);
+                return -1;
+            }
         }
 
         if (*end == ',')