diff --git a/src/config/config.h b/src/config/config.h
new file mode 100644
index 0000000..a176534
--- /dev/null
+++ b/src/config/config.h
@@ -0,0 +1,10 @@
+#pragma once
+#include <stdint.h>
+
+/// Wrangler for assorted compile-time configuration and constants.
+namespace config {
+
+/// Max number of extruders
+static constexpr uint8_t tool_count = 5U;
+
+} // namespace config
diff --git a/src/modules/permanent_storage.cpp b/src/modules/permanent_storage.cpp
index d21eb2d..1c23542 100644
--- a/src/modules/permanent_storage.cpp
+++ b/src/modules/permanent_storage.cpp
@@ -1,6 +1,7 @@
 #include "permanent_storage.h"
 #include "../hal/eeprom.h"
 #include "globals.h"
+#include "../config/config.h"
 
 #include <stddef.h>
 
@@ -18,7 +19,7 @@ namespace permanent_storage {
 /// needs to be changed to force an EEPROM erase.
 struct eeprom_t {
     uint8_t eepromLengthCorrection; ///< Legacy bowden length correction
-    uint16_t eepromBowdenLen[5]; ///< Bowden length for each filament
+    uint16_t eepromBowdenLen[config::tool_count]; ///< Bowden length for each filament
     uint8_t eepromFilamentStatus[3]; ///< Majority vote status of eepromFilament wear leveling
     uint8_t eepromFilament[800]; ///< Top nibble status, bottom nibble last filament loaded
     uint8_t eepromDriveErrorCountH;