diff --git a/source/src/command.cpp b/source/src/command.cpp
index ff43fdba..acf5947c 100644
--- a/source/src/command.cpp
+++ b/source/src/command.cpp
@@ -463,6 +463,11 @@ char *parseword(const char *&p, int arg, int &infix)                       // pa
 
 char *conc(const char **w, int n, bool space)
 {
+    if(n < 0)
+    {  // auto-determine number of strings
+        n = 0;
+        while(w[n] && w[n][0]) n++;
+    }
     int len = space ? max(n-1, 0) : 0;
     loopj(n) len += (int)strlen(w[j]);
     char *r = newstring("", len);
@@ -1745,9 +1750,7 @@ void listoptions(char *s)
     const char *optionnames[] = { "entities", "ents", "weapons", "teamnames", "teamnames-abbrv", "punctuations", "crosshairnames", "" };
     const char **optionlists[] = { optionnames, entnames + 1, entnames + 1, gunnames, teamnames, teamnames_s, punctnames, crosshairnames };
     const char **listp = optionlists[getlistindex(s, optionnames, true, -1) + 1];
-    int num = 0;
-    while(listp[num] && listp[num][0]) num++;
-    commandret = conc(listp, num, true);
+    commandret = conc(listp, -1, true);
 }
 COMMAND(listoptions, "s");
 
diff --git a/source/src/tools.cpp b/source/src/tools.cpp
index 7c301968..7209b5f5 100644
--- a/source/src/tools.cpp
+++ b/source/src/tools.cpp
@@ -432,6 +432,11 @@ int getlistindex(const char *key, const char *list[], bool acceptnumeric, int de
         int i = (int)strtol(key, NULL, 0);
         if(i >= 0 && i < max) return i;
     }
+#if !defined(STANDALONE) && defined(_DEBUG)
+    char *opts = conc(list, -1, true);
+    if(*key) clientlogf("warning: unknown token \"%s\" (not in list [%s])", key, opts);
+    delstring(opts);
+#endif
     return deflt;
 }