diff -ruN proftpd-1.2.10-old/src/main.c proftpd-1.2.10/src/main.c
--- proftpd-1.2.10-old/src/main.c	2006-11-20 14:06:17.000000000 +0100
+++ proftpd-1.2.10/src/main.c	2006-11-20 14:07:03.000000000 +0100
@@ -118,6 +118,8 @@
 
 static char sbuf[PR_TUNABLE_BUFFER_SIZE] = {'\0'};
 
+#define PR_DEFAULT_CMD_BUFSZ 512
+
 static char **Argv = NULL;
 static char *LastArgv = NULL;
 static const char *PidPath = PID_FILE_PATH;
@@ -810,16 +812,25 @@
       reset_timer(TIMER_IDLE, NULL);
 
     if (cmd_buf_size == -1) {
-      long *buf_size = get_param_ptr(main_server->conf,
-        "CommandBufferSize", FALSE);
-
-      if (buf_size == NULL || *buf_size <= 0)
-        cmd_buf_size = 512;
+      int *bufsz = get_param_ptr(main_server->conf, "CommandBufferSize", FALSE);
+      if (bufsz == NULL) {
+        cmd_buf_size = PR_DEFAULT_CMD_BUFSZ;
+
+      } else if (*bufsz <= 0) {
+        pr_log_pri(PR_LOG_WARNING, "invalid CommandBufferSize size (%d) "
+          "given, using default buffer size (%u) instead",
+          *bufsz, PR_DEFAULT_CMD_BUFSZ);
+        cmd_buf_size = PR_DEFAULT_CMD_BUFSZ;
+
+      } else if (*bufsz + 1 > sizeof(buf)) {
+        pr_log_pri(PR_LOG_WARNING, "invalid CommandBufferSize size (%d) "
+          "given, using default buffer size (%u) instead",
+          *bufsz, PR_DEFAULT_CMD_BUFSZ);
+        cmd_buf_size = PR_DEFAULT_CMD_BUFSZ;
 
-      else if (*buf_size + 1 > sizeof(buf)) {
-	pr_log_pri(PR_LOG_WARNING, "Invalid CommandBufferSize size given. "
-          "Resetting to 512.");
-	cmd_buf_size = 512;
+      } else {
+        pr_log_debug(DEBUG1, "setting CommandBufferSize to %d", *bufsz);
+        cmd_buf_size = (long) *bufsz;
       }
     }