Index: encoding.c
===================================================================
--- encoding.c	(revision 31953)
+++ encoding.c	(working copy)
@@ -1421,7 +1421,11 @@
     const char *codeset = nl_langinfo_codeset();
     char cp[sizeof(int) * 3 + 4];
     if (!codeset) {
-	snprintf(cp, sizeof(cp), "CP%d", GetConsoleCP());
+	UINT codepage = GetConsoleCP();
+	if(codepage==0) {
+	    codepage = GetACP();
+	}
+	snprintf(cp, sizeof(cp), "CP%d", codepage); 
 	codeset = cp;
     }
     return rb_usascii_str_new2(codeset);