diff -r 56e7f4b4313b src/settings_gui.cpp
--- a/src/settings_gui.cpp	Sun Nov 16 10:33:00 2008 +0100
+++ b/src/settings_gui.cpp	Sun Nov 16 10:51:27 2008 +0100
@@ -872,7 +872,7 @@
 	static GameSettings *patches_ptr;  ///< Pointer to the game settings being displayed and modified
 
 	int page;
-	int entry;
+	PatchEntry *valuewindow_entry; ///< If non-NULL, pointer to patch setting for which a value-entering window has been opened
 	PatchEntry *depressed_entry; ///< If non-NULL, pointer to a clicked numeric patch setting (with a depressed left or right button)
 
 	PatchesSelectionWindow(const WindowDesc *desc) : Window(desc)
@@ -895,6 +895,7 @@
 			first_time = false;
 		}
 
+		valuewindow_entry = NULL; // No patch entry for which a entry window is opened
 		depressed_entry = NULL; // No numeric patch setting buttons are depressed
 
 		page = 0;
@@ -1008,7 +1009,7 @@
 						/* Show the correct currency-translated value */
 						if (sd->desc.flags & SGF_CURRENCY) value *= _currency->rate;
 
-						this->entry = btn;
+						valuewindow_entry = &page->entries[btn];
 						SetDParam(0, value);
 						ShowQueryString(STR_CONFIG_PATCHES_INT32, STR_CONFIG_PATCHES_QUERY_CAPT, 10, 100, this, CS_NUMERAL, QSF_NONE);
 					}
@@ -1043,14 +1044,14 @@
 	virtual void OnQueryTextFinished(char *str)
 	{
 		if (!StrEmpty(str)) {
-			const PatchEntry *pe = &_patches_page[this->page].entries[this->entry];
-			const SettingDesc *sd = pe->setting;
+			assert(valuewindow_entry != NULL);
+			const SettingDesc *sd = valuewindow_entry->setting;
 			int32 value = atoi(str);
 
 			/* Save the correct currency-translated value */
 			if (sd->desc.flags & SGF_CURRENCY) value /= _currency->rate;
 
-			SetPatchValue(pe->index, value);
+			SetPatchValue(valuewindow_entry->index, value);
 			this->SetDirty();
 		}
 	}