diff --git a/source/src/protocol.cpp b/source/src/protocol.cpp
index 0b83f22f..61d1c905 100644
--- a/source/src/protocol.cpp
+++ b/source/src/protocol.cpp
@@ -207,12 +207,45 @@ void freegzbuf(ucharbuf *p)  // free a ucharbuf created by getgzbuf()
     }
 }
 
+//#define FILENAMESALLLOWERCASE
+
+bool validmapname(const char *s) // checks for length, allowed chars and special DOS filenames
+{
+    int len = strlen(s);
+    if(len > MAXMAPNAMELEN) return false;
+    if(len == 3 || len == 4)
+    {
+        char uc[4];
+        loopi(3) uc[i] = toupper(s[i]);
+        uc[3] = '\0';
+        const char *resd = "COMLPTCONPRNAUXNUL", *fnd = strstr(resd, uc);
+        if(fnd)
+        {
+            int pos = (int) (fnd - resd);
+            if(pos == 0 || pos == 3)
+            {
+                if(isdigit(s[3])) return false; // COMx, LPTx
+            }
+            else if(pos % 3 == 0) return false; // CON, PRN, AUX, NUL
+        }
+    }
+    while(*s != '\0')
+    {
+#ifdef FILENAMESALLLOWERCASE
+        if(!islower(*s) && !isdigit(*s) && *s != '_' && *s != '-' && *s != '.') return false;
+#else
+        if(!isalnum(*s) && *s != '_' && *s != '-' && *s != '.') return false;
+#endif
+        ++s;
+    }
+    return true;
+}
+
+
 // filter text according to rules
 // dst can be identical to src; dst needs to be of size "min(len, strlen(s)) + 1"
 // returns dst
 
-//#define FILENAMESALLLOWERCASE
-
 char *filtertext(char *dst, const char *src, int flags, int len)
 {
     char *res = dst;
diff --git a/source/src/protocol.h b/source/src/protocol.h
index 0c6f3490..58d10090 100644
--- a/source/src/protocol.h
+++ b/source/src/protocol.h
@@ -9,6 +9,7 @@
 #define DEMO_VERSION 2                  // bump when demo format changes
 #define DEMO_MAGIC "ASSAULTCUBE_DEMO"
 #define DEMO_MINTIME 10000              // don't keep demo recordings with less than 10 seconds
+#define MAXMAPNAMELEN 31
 #define MAXMAPSENDSIZE 65536
 #define MAXCFGFILESIZE 65536
 #define MAXGZMSGSIZE 65536
diff --git a/source/src/protos.h b/source/src/protos.h
index c6a5a8ca..480b53a1 100644
--- a/source/src/protos.h
+++ b/source/src/protos.h
@@ -1062,6 +1062,7 @@ extern void getstring(char *t, ucharbuf &p, int len = MAXTRANS);
 extern void putgzbuf(vector<uchar> &d, vector<uchar> &s); // zips a vector into a stream, stored in another vector
 extern ucharbuf *getgzbuf(ucharbuf &p); // fetch a gzipped buffer; needs to be freed properly later
 extern void freegzbuf(ucharbuf *p);  // free a ucharbuf created by getgzbuf()
+extern bool validmapname(const char *s); // checks for length, allowed chars and special DOS filenames
 extern char *filtertext(char *dst, const char *src, int flags, int len = sizeof(string)-1);
 extern void filterrichtext(char *dst, const char *src, int len = sizeof(string)-1);
 extern void filterlang(char *d, const char *s);
diff --git a/source/src/serverfiles.h b/source/src/serverfiles.h
index f960672c..b13f6a0d 100644
--- a/source/src/serverfiles.h
+++ b/source/src/serverfiles.h
@@ -83,37 +83,43 @@ struct servermap  // in-memory version of a map file on a server
 
         stream *f = NULL;
         int restofhead;
+        string filename;
+
+        if(!validmapname(fname)) err = "illegal filename";
+        if(err) goto loadfailed;
 
         // load map files, prepare sendmap buffer
-        defformatstring(filename)("%s%s.cfg", fpath, fname);
-        path(filename);
-        uchar *cfgraw = (uchar *)loadfile(filename, &cfglen);
-        if(cfgraw)
         {
-            tigerhash(cfghash, cfgraw, cfglen);
-            loopk(cfglen) if(cfgraw[k] > 0x7f || (cfgraw[k] < 0x20 && !isspace(cfgraw[k]))) err = "illegal chars in cfg file";
-        }
-        formatstring(filename)("%s%s.cgz", fpath, fname);
-        path(filename);
-        cgzraw = (uchar *)loadfile(filename, &cgzlen);
-        if(cgzraw) tigerhash(cgzhash, cgzraw, cgzlen);
-        if(!cgzraw) err = "loading cgz failed";
-        else if(cfglen > MAXCFGFILESIZE) err = "cfg file too big";
-        else if(cgzlen >= MAXMAPSENDSIZE) err = "cgz file too big";
-        else if(cfgraw)
-        {
-            uLongf gzbufsize = GZBUFSIZE;
-            ASSERT(GZBUFSIZE < FLOORPLANBUFSIZE);
-            if(compress2(staticbuffer, &gzbufsize, cfgraw, cfglen, 9) != Z_OK) gzbufsize = 0;
-            cfggzlen = (int) gzbufsize;
-            if(cgzlen + cfggzlen < MAXMAPSENDSIZE)
-            { // map is small enough to be sent
-                cfgrawgz = new uchar[cfggzlen];
-                memcpy(cfgrawgz, staticbuffer, cfggzlen);
+            formatstring(filename)("%s%s.cfg", fpath, fname);
+            path(filename);
+            uchar *cfgraw = (uchar *)loadfile(filename, &cfglen);
+            if(cfgraw)
+            {
+                tigerhash(cfghash, cfgraw, cfglen);
+                loopk(cfglen) if(cfgraw[k] > 0x7f || (cfgraw[k] < 0x20 && !isspace(cfgraw[k]))) err = "illegal chars in cfg file";
             }
-            else err = "cgz + cfg.gz too big to send";
+            formatstring(filename)("%s%s.cgz", fpath, fname);
+            path(filename);
+            cgzraw = (uchar *)loadfile(filename, &cgzlen);
+            if(cgzraw) tigerhash(cgzhash, cgzraw, cgzlen);
+            if(!cgzraw) err = "loading cgz failed";
+            else if(cfglen > MAXCFGFILESIZE) err = "cfg file too big";
+            else if(cgzlen >= MAXMAPSENDSIZE) err = "cgz file too big";
+            else if(cfgraw)
+            {
+                uLongf gzbufsize = GZBUFSIZE;
+                ASSERT(GZBUFSIZE < FLOORPLANBUFSIZE);
+                if(compress2(staticbuffer, &gzbufsize, cfgraw, cfglen, 9) != Z_OK) gzbufsize = 0;
+                cfggzlen = (int) gzbufsize;
+                if(cgzlen + cfggzlen < MAXMAPSENDSIZE)
+                { // map is small enough to be sent
+                    cfgrawgz = new uchar[cfggzlen];
+                    memcpy(cfgrawgz, staticbuffer, cfggzlen);
+                }
+                else err = "cgz + cfg.gz too big to send";
+            }
+            DELETEA(cfgraw);
         }
-        DELETEA(cfgraw);
         if(err) goto loadfailed;
 
         // extract entity data and header info; compile map statistics; create floorplan
diff --git a/source/src/tools.h b/source/src/tools.h
index b882d5d4..f8f5b2a8 100644
--- a/source/src/tools.h
+++ b/source/src/tools.h
@@ -139,35 +139,6 @@ struct stringformatter
 #define defformatstring(d) string d; formatstring(d)
 #define defvformatstring(d,last,fmt) string d; { va_list ap; va_start(ap, last); vformatstring(d, fmt, ap); va_end(ap); }
 
-#define MAXMAPNAMELEN 64
-inline bool validmapname(const char *s)
-{
-    int len = strlen(s);
-    if(len > MAXMAPNAMELEN) return false;
-    if(len == 3 || len == 4)
-    {
-        char uc[4];
-        loopi(3) uc[i] = toupper(s[i]);
-        uc[3] = '\0';
-        const char *resd = "COMLPTCONPRNAUXNUL", *fnd = strstr(resd, uc);
-        if(fnd)
-        {
-            int pos = (int) (fnd - resd);
-            if(pos == 0 || pos == 3)
-            {
-                if(isdigit(s[3])) return false; // COMx, LPTx
-            }
-            else if(pos % 3 == 0) return false; // CON, PRN, AUX, NUL
-        }
-    }
-    while(*s != '\0')
-    {
-        if(!isalnum(*s) && *s != '_' && *s != '-' && *s != '.') return false;
-        ++s;
-    }
-    return true;
-}
-
 #define loopv(v)    for(int i = 0; i<(v).length(); i++)
 #define loopvj(v)   for(int j = 0; j<(v).length(); j++)
 #define loopvk(v)   for(int k = 0; k<(v).length(); k++)