Index: src/fios.h
===================================================================
--- src/fios.h	(revision 27726)
+++ src/fios.h	(working copy)
@@ -81,10 +81,9 @@
 
 enum FileSlots {
 	/**
-	 * Slot used for the GRF scanning and such. This slot cannot be reused
-	 * as it will otherwise cause issues when pressing "rescan directories".
-	 * It can furthermore not be larger than LAST_GRF_SLOT as that complicates
-	 * the testing for "too much NewGRFs".
+	 * Slot used for the GRF scanning and such.
+	 * This slot is used for all temporary accesses to files when scanning/testing files,
+	 * and thus cannot be used for any long-term usage.
 	 */
 	CONFIG_SLOT    =  0,
 	/** Slot for the sound. */
@@ -91,10 +90,8 @@
 	SOUND_SLOT     =  1,
 	/** First slot usable for (New)GRFs used during the game. */
 	FIRST_GRF_SLOT =  2,
-	/** Last slot usable for (New)GRFs used during the game. */
-	LAST_GRF_SLOT  = 63,
 	/** Maximum number of slots. */
-	MAX_FILE_SLOTS = 64
+	MAX_FILE_SLOTS = 128,
 };
 
 /** Deals with finding savegames */
Index: src/network/core/config.h
===================================================================
--- src/network/core/config.h	(revision 27726)
+++ src/network/core/config.h	(working copy)
@@ -55,8 +55,7 @@
 
 /**
  * Maximum number of GRFs that can be sent.
- * This value is related to number of handles (files) OpenTTD can open.
- * This is currently 64. Two are used for configuration and sound.
+ * This limit is reached when PACKET_UDP_SERVER_RESPONSE reaches the maximum size of SEND_MTU bytes.
  */
 static const uint NETWORK_MAX_GRF_COUNT           =   62;
 
Index: src/newgrf.cpp
===================================================================
--- src/newgrf.cpp	(revision 27726)
+++ src/newgrf.cpp	(working copy)
@@ -8860,7 +8860,7 @@
 		if (stage == GLS_ACTIVATION && !HasBit(config->flags, GCF_RESERVED)) return;
 	}
 
-	if (file_index > LAST_GRF_SLOT) {
+	if (file_index >= MAX_FILE_SLOTS) {
 		DEBUG(grf, 0, "'%s' is not loaded as the maximum number of GRFs has been reached", filename);
 		config->status = GCS_DISABLED;
 		config->error  = new GRFError(STR_NEWGRF_ERROR_MSG_FATAL, STR_NEWGRF_ERROR_TOO_MANY_NEWGRFS_LOADED);
@@ -9263,6 +9263,7 @@
 		}
 
 		uint slot = file_index;
+		uint num_non_static = 0;
 
 		_cur.stage = stage;
 		for (GRFConfig *c = _grfconfig; c != NULL; c = c->next) {
@@ -9277,6 +9278,16 @@
 			}
 
 			if (stage == GLS_LABELSCAN) InitNewGRFFile(c);
+
+			if (!HasBit(c->flags, GCF_STATIC) && !HasBit(c->flags, GCF_SYSTEM)) {
+				if (num_non_static == NETWORK_MAX_GRF_COUNT) {
+					DEBUG(grf, 0, "'%s' is not loaded as the maximum number of GRFs has been reached", c->filename);
+					c->status = GCS_DISABLED;
+					c->error  = new GRFError(STR_NEWGRF_ERROR_MSG_FATAL, STR_NEWGRF_ERROR_TOO_MANY_NEWGRFS_LOADED);
+					continue;
+				}
+				num_non_static++;
+			}
 			LoadNewGRFFile(c, slot++, stage, subdir);
 			if (stage == GLS_RESERVE) {
 				SetBit(c->flags, GCF_RESERVED);
Index: src/newgrf_gui.cpp
===================================================================
--- src/newgrf_gui.cpp	(revision 27726)
+++ src/newgrf_gui.cpp	(working copy)
@@ -39,10 +39,6 @@
 #include <map>
 #include "safeguards.h"
 
-/* Maximum number of NewGRFs that may be loaded. Six reserved slots are:
- * 0 - config, 1 - sound, 2 - base, 3 - logos, 4 - climate, 5 - extra */
-static const int MAX_NEWGRFS = MAX_FILE_SLOTS - 6;
-
 /**
  * Show the first NewGRF error we can find.
  */
@@ -1509,7 +1505,7 @@
 	{
 		if (this->avail_sel == NULL || !this->editable || HasBit(this->avail_sel->flags, GCF_INVALID)) return false;
 
-		int count = 0;
+		uint count = 0;
 		GRFConfig **entry = NULL;
 		GRFConfig **list;
 		/* Find last entry in the list, checking for duplicate grfid on the way */
@@ -1522,7 +1518,7 @@
 			count++;
 		}
 		if (entry == NULL) entry = list;
-		if (count >= MAX_NEWGRFS) {
+		if (count >= NETWORK_MAX_GRF_COUNT) {
 			ShowErrorMessage(STR_NEWGRF_TOO_MANY_NEWGRFS, INVALID_STRING_ID, WL_INFO);
 			return false;
 		}