diff --git a/polymer/eduke32/build/include/common.h b/polymer/eduke32/build/include/common.h
index e54dde762..beeadf981 100644
--- a/polymer/eduke32/build/include/common.h
+++ b/polymer/eduke32/build/include/common.h
@@ -62,6 +62,7 @@ void G_LoadGroupsInDir(const char *dirname);
 void G_DoAutoload(const char *dirname);
 
 char *dup_filename(const char *fn);
+int32_t maybe_append_ext(char *wbuf, int32_t wbufsiz, const char *fn, const char *ext);
 
 // timer defs for profiling function chunks the simple way
 #define EDUKE32_TMRDEF int32_t t[20], ti=0; const char *tmrstr=__func__; fprintf(stderr,"%s\n",tmrstr); t[ti++]=getticks();
diff --git a/polymer/eduke32/source/common.c b/polymer/eduke32/source/common.c
index bd369044b..57fa1dc71 100644
--- a/polymer/eduke32/source/common.c
+++ b/polymer/eduke32/source/common.c
@@ -315,3 +315,18 @@ char *dup_filename(const char *fn)
 
     return Bstrncpyz(buf, fn, BMAX_PATH);
 }
+
+
+// Copy FN to WBUF and append an extension if it's not there, which is checked
+// case-insensitively.
+// Returns: 1 if not all characters could be written to WBUF, 0 else.
+int32_t maybe_append_ext(char *wbuf, int32_t wbufsiz, const char *fn, const char *ext)
+{
+    const int32_t slen=Bstrlen(fn), extslen=Bstrlen(ext);
+    const int32_t haveext = (slen>=extslen && Bstrcasecmp(&fn[slen-extslen], ext)==0);
+
+    Bassert((intptr_t)wbuf != (intptr_t)fn);  // no aliasing
+
+    // If 'fn' has no extension suffixed, append one.
+    return (Bsnprintf(wbuf, wbufsiz, "%s%s", fn, haveext ? "" : ext) >= wbufsiz);
+}
diff --git a/polymer/eduke32/source/game.c b/polymer/eduke32/source/game.c
index 4032986cc..7c7397d6a 100644
--- a/polymer/eduke32/source/game.c
+++ b/polymer/eduke32/source/game.c
@@ -8961,17 +8961,10 @@ static void G_CheckCommandLine(int32_t argc, const char **argv)
                     ud.m_coop--;
                     break;
                 case 'd':
-                {
-                    char *dot;
-
                     c++;
-                    Bstrcpy(g_firstDemoFile,c);
-                    dot = Bstrchr(g_firstDemoFile,'.');
-                    if (!dot && Bstrlen(g_firstDemoFile)+4 < sizeof(g_firstDemoFile))
-                        Bstrcat(g_firstDemoFile,".edm");
+                    maybe_append_ext(g_firstDemoFile, sizeof(g_firstDemoFile), c, ".edm");
                     initprintf("Play demo %s.\n",g_firstDemoFile);
                     break;
-                }
                 case 'g':
                     c++;
                     if (*c)
diff --git a/polymer/eduke32/source/osdcmds.c b/polymer/eduke32/source/osdcmds.c
index 56cbb1f3d..a8fd4c194 100644
--- a/polymer/eduke32/source/osdcmds.c
+++ b/polymer/eduke32/source/osdcmds.c
@@ -167,13 +167,21 @@ static int32_t osdcmd_map(const osdfuncparm_t *parm)
     int32_t i;
     char filename[BMAX_PATH];
 
-    if (parm->numparms != 1)
+    const int32_t wildcardp = parm->numparms==1 &&
+        (Bstrchr(parm->parms[0], '*') != NULL);
+
+    if (parm->numparms != 1 || wildcardp)
     {
         CACHE1D_FIND_REC *r;
         fnlist_t fnlist = FNLIST_INITIALIZER;
         int32_t maxwidth = 0;
 
-        fnlist_getnames(&fnlist, "/", "*.MAP", -1, 0);
+        if (wildcardp)
+            maybe_append_ext(filename, sizeof(filename), parm->parms[0], ".map");
+        else
+            Bstrcpy(filename, "*.MAP");
+
+        fnlist_getnames(&fnlist, "/", filename, -1, 0);
 
         for (r=fnlist.findfiles; r; r=r->next)
             maxwidth = max((unsigned)maxwidth, Bstrlen(r->name));
@@ -211,9 +219,7 @@ static int32_t osdcmd_map(const osdfuncparm_t *parm)
     }
 #endif
 
-    strcpy(filename,parm->parms[0]);
-    if (strchr(filename,'.') == 0)
-        strcat(filename,".map");
+    maybe_append_ext(filename, sizeof(filename), parm->parms[0], ".map");
 
     if ((i = kopen4loadfrommod(filename,0)) < 0)
     {