diff --git a/include/PinMapping.h b/include/PinMapping.h
index 45f89a7c..eab9e50b 100644
--- a/include/PinMapping.h
+++ b/include/PinMapping.h
@@ -27,12 +27,12 @@ struct PinMapping_t {
     gpio_num_t cmt_gpio3;
     gpio_num_t cmt_sdio;
 
-    int8_t w5500_mosi;
-    int8_t w5500_miso;
-    int8_t w5500_sclk;
-    int8_t w5500_cs;
-    int8_t w5500_int;
-    int8_t w5500_rst;
+    gpio_num_t w5500_mosi;
+    gpio_num_t w5500_miso;
+    gpio_num_t w5500_sclk;
+    gpio_num_t w5500_cs;
+    gpio_num_t w5500_int;
+    gpio_num_t w5500_rst;
 
 #if CONFIG_ETH_USE_ESP32_EMAC
     int8_t eth_phy_addr;
diff --git a/include/W5500.h b/include/W5500.h
index d85cb016..0a6d5f8a 100644
--- a/include/W5500.h
+++ b/include/W5500.h
@@ -17,7 +17,7 @@ public:
     W5500& operator=(const W5500&) = delete;
     ~W5500();
 
-    static std::unique_ptr<W5500> setup(int8_t pin_mosi, int8_t pin_miso, int8_t pin_sclk, int8_t pin_cs, int8_t pin_int, int8_t pin_rst);
+    static std::unique_ptr<W5500> setup(gpio_num_t pin_mosi, gpio_num_t pin_miso, gpio_num_t pin_sclk, gpio_num_t pin_cs, gpio_num_t pin_int, gpio_num_t pin_rst);
     String macAddress();
 
 private:
diff --git a/platformio.ini b/platformio.ini
index 8db28883..bb42eecd 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -281,11 +281,11 @@ build_flags = ${env.build_flags}
     -DCMT_GPIO2=GPIO_NUM_3
     -DCMT_GPIO3=GPIO_NUM_8
     -DCMT_SDIO=GPIO_NUM_5
-    -DW5500_MOSI=40
-    -DW5500_MISO=41
-    -DW5500_SCLK=39
-    -DW5500_CS=42
-    -DW5500_INT=44
-    -DW5500_RST=43
+    -DW5500_MOSI=GPIO_NUM_40
+    -DW5500_MISO=GPIO_NUM_41
+    -DW5500_SCLK=GPIO_NUM_39
+    -DW5500_CS=GPIO_NUM_42
+    -DW5500_INT=GPIO_NUM_44
+    -DW5500_RST=GPIO_NUM_43
     -DARDUINO_USB_MODE=1
     -DARDUINO_USB_CDC_ON_BOOT=1
diff --git a/src/PinMapping.cpp b/src/PinMapping.cpp
index 5253522e..e3b9b669 100644
--- a/src/PinMapping.cpp
+++ b/src/PinMapping.cpp
@@ -86,27 +86,27 @@
 #endif
 
 #ifndef W5500_MOSI
-#define W5500_MOSI -1
+#define W5500_MOSI GPIO_NUM_NC
 #endif
 
 #ifndef W5500_MISO
-#define W5500_MISO -1
+#define W5500_MISO GPIO_NUM_NC
 #endif
 
 #ifndef W5500_SCLK
-#define W5500_SCLK -1
+#define W5500_SCLK GPIO_NUM_NC
 #endif
 
 #ifndef W5500_CS
-#define W5500_CS -1
+#define W5500_CS GPIO_NUM_NC
 #endif
 
 #ifndef W5500_INT
-#define W5500_INT -1
+#define W5500_INT GPIO_NUM_NC
 #endif
 
 #ifndef W5500_RST
-#define W5500_RST -1
+#define W5500_RST GPIO_NUM_NC
 #endif
 
 #if CONFIG_ETH_USE_ESP32_EMAC
@@ -286,12 +286,12 @@ bool PinMappingClass::isValidCmt2300Config() const
 
 bool PinMappingClass::isValidW5500Config() const
 {
-    return _pinMapping.w5500_mosi >= 0
-        && _pinMapping.w5500_miso >= 0
-        && _pinMapping.w5500_sclk >= 0
-        && _pinMapping.w5500_cs >= 0
-        && _pinMapping.w5500_int >= 0
-        && _pinMapping.w5500_rst >= 0;
+    return _pinMapping.w5500_mosi > GPIO_NUM_NC
+        && _pinMapping.w5500_miso > GPIO_NUM_NC
+        && _pinMapping.w5500_sclk > GPIO_NUM_NC
+        && _pinMapping.w5500_cs > GPIO_NUM_NC
+        && _pinMapping.w5500_int > GPIO_NUM_NC
+        && _pinMapping.w5500_rst > GPIO_NUM_NC;
 }
 
 #if CONFIG_ETH_USE_ESP32_EMAC
diff --git a/src/W5500.cpp b/src/W5500.cpp
index bf539434..b785a962 100644
--- a/src/W5500.cpp
+++ b/src/W5500.cpp
@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
- * Copyright (C) 2024 Thomas Basler and others
+ * Copyright (C) 2024-2025 Thomas Basler and others
  */
 
 #include "W5500.h"
@@ -56,19 +56,17 @@ W5500::~W5500()
     // TODO(LennartF22): support cleanup at some point?
 }
 
-std::unique_ptr<W5500> W5500::setup(int8_t pin_mosi, int8_t pin_miso, int8_t pin_sclk, int8_t pin_cs, int8_t pin_int, int8_t pin_rst)
+std::unique_ptr<W5500> W5500::setup(gpio_num_t pin_mosi, gpio_num_t pin_miso, gpio_num_t pin_sclk, gpio_num_t pin_cs, gpio_num_t pin_int, gpio_num_t pin_rst)
 {
-    gpio_reset_pin(static_cast<gpio_num_t>(pin_rst));
-    gpio_set_level(static_cast<gpio_num_t>(pin_rst), 0);
-    gpio_set_direction(static_cast<gpio_num_t>(pin_rst), GPIO_MODE_OUTPUT);
+    gpio_reset_pin(pin_rst);
+    gpio_set_level(pin_rst, 0);
+    gpio_set_direction(pin_rst, GPIO_MODE_OUTPUT);
 
-    gpio_reset_pin(static_cast<gpio_num_t>(pin_cs));
-    gpio_reset_pin(static_cast<gpio_num_t>(pin_int));
+    gpio_reset_pin(pin_cs);
+    gpio_reset_pin(pin_int);
 
     auto bus_config = std::make_shared<SpiBusConfig>(
-        static_cast<gpio_num_t>(pin_mosi),
-        static_cast<gpio_num_t>(pin_miso),
-        static_cast<gpio_num_t>(pin_sclk));
+        pin_mosi, pin_miso, pin_sclk);
 
     spi_device_interface_config_t device_config {
         .command_bits = 16, // actually address phase
@@ -93,12 +91,12 @@ std::unique_ptr<W5500> W5500::setup(int8_t pin_mosi, int8_t pin_miso, int8_t pin
 
     // Reset sequence
     delayMicroseconds(500);
-    gpio_set_level(static_cast<gpio_num_t>(pin_rst), 1);
+    gpio_set_level(pin_rst, 1);
     delayMicroseconds(1000);
 
     if (!connection_check_spi(spi))
         return nullptr;
-    if (!connection_check_interrupt(static_cast<gpio_num_t>(pin_int)))
+    if (!connection_check_interrupt(pin_int))
         return nullptr;
 
     // Use Arduino functions to temporarily attach interrupt to enable the GPIO ISR service
@@ -107,9 +105,9 @@ std::unique_ptr<W5500> W5500::setup(int8_t pin_mosi, int8_t pin_miso, int8_t pin
     detachInterrupt(pin_int);
 
     // Return to default state once again after connection check and temporary interrupt registration
-    gpio_reset_pin(static_cast<gpio_num_t>(pin_int));
+    gpio_reset_pin(pin_int);
 
-    return std::unique_ptr<W5500>(new W5500(spi, static_cast<gpio_num_t>(pin_int)));
+    return std::unique_ptr<W5500>(new W5500(spi, pin_int));
 }
 
 String W5500::macAddress()