diff --git a/.github/workflows/githubci.yml b/.github/workflows/githubci.yml
index ca9b31b..25b79fa 100644
--- a/.github/workflows/githubci.yml
+++ b/.github/workflows/githubci.yml
@@ -19,10 +19,10 @@ jobs:
     - name: pre-install
       run: bash ci/actions_install.sh
 
-    - name: install SD logger example dependency
+    - name: install SdFat logger example dependency
       run: |
         arduino-cli lib update-index
-        arduino-cli lib install SD
+        arduino-cli lib install "SdFat - Adafruit Fork"
 
     - name: test platforms
       run: python3 ci/build_platform.py main_platforms
diff --git a/README.md b/README.md
index 04e5e78..b94203d 100644
--- a/README.md
+++ b/README.md
@@ -14,8 +14,8 @@ not universal across GPS manufacturers.
 ## Getting started
 
 1. In the Arduino IDE Library Manager, search for **Adafruit GPS** and install
-   **Adafruit GPS Library**. For the `shield_sdlog` example, also install **SD**
-   by Arduino from Library Manager.
+   **Adafruit GPS Library**. For the `shield_sdlog` example, also install
+   **SdFat - Adafruit Fork** by Bill Greiman from Library Manager.
 2. Follow the wiring guide for your module:
    [Ultimate GPS](https://learn.adafruit.com/adafruit-ultimate-gps) or
    [PA1010D](https://learn.adafruit.com/adafruit-mini-gps-pa1010d-module).
@@ -74,9 +74,11 @@ a **parsing** sketch turns that text into individual readings.
 
 **SD logging** writes files to a separate SD card. The `shield_sdlog` example
 uses GPS pins D8/D7, the hardware SPI pins, and SD chip select D10. It writes raw
-NMEA text into files such as `GPSLOG00.TXT`. With `LOG_FIXONLY` set to `false`, it
-also saves sentences while the GPS has no position fix. Set it to `true` if you
-only want records with a fix.
+NMEA text into files named `GPSLOG0000.TXT` through `GPSLOG9999.TXT`, using
+SdFat's long-filename support. Each start creates a new file; if all names are
+used, the logger stops instead of reopening an old log. With `LOG_FIXONLY` set
+to `false`, it also saves sentences while the GPS has no position fix. Set it
+to `true` if you only want records with a fix.
 
 The Uno and Metro 328 have only 2 KB of RAM. SD logging leaves limited room for
 additional buffers and variables; keep constant print messages in `F()` when
diff --git a/examples/shield_sdlog/shield_sdlog.ino b/examples/shield_sdlog/shield_sdlog.ino
index 9ed8467..5f03a6c 100644
--- a/examples/shield_sdlog/shield_sdlog.ino
+++ b/examples/shield_sdlog/shield_sdlog.ino
@@ -1,7 +1,7 @@
 #include <SPI.h>
 #include <Adafruit_GPS.h>
 #include <SoftwareSerial.h>
-#include <SD.h>
+#include <SdFat_Adafruit_Fork.h>
 #include <avr/sleep.h>
 
 // Ladyada's logger modified by Bill Greiman to use the SdFat library
@@ -36,6 +36,7 @@ bool usingInterrupt = false;
 #define chipSelect 10
 #define ledPin 13
 
+SdFat SD;
 File logfile;
 
 // read a Hex value and return the decimal equivalent
@@ -96,18 +97,19 @@ void setup() {
     error(2);
   }
   char filename[15];
-  strcpy(filename, "GPSLOG00.TXT");
-  for (uint8_t i = 0; i < 100; i++) {
-    filename[6] = '0' + i/10;
-    filename[7] = '0' + i%10;
-    // create if does not exist, do not open existing, write, sync after write
+  strcpy(filename, "GPSLOG0000.TXT");
+  for (uint16_t i = 0; i < 10000; i++) {
+    filename[6] = '0' + i/1000;
+    filename[7] = '0' + (i/100)%10;
+    filename[8] = '0' + (i/10)%10;
+    filename[9] = '0' + i%10;
+    // Find an unused long filename, then create it without opening an old log.
     if (! SD.exists(filename)) {
       break;
     }
   }
 
-  logfile = SD.open(filename, FILE_WRITE);
-  if( ! logfile ) {
+  if (!logfile.open(filename, O_WRONLY | O_CREAT | O_EXCL)) {
     Serial.print(F("Couldnt create "));
     Serial.println(filename);
     error(3);
@@ -131,6 +133,16 @@ void setup() {
   GPS.sendCommand(F(PGCMD_NOANTENNA));
   GPS.sendCommand(F(CDCMD_NOANTENNA));
 
+  // Drain startup command replies before the first SD write. Their rapid
+  // arrival can otherwise reuse a GPS receive buffer while it is being saved.
+  uint32_t start = millis();
+  while (millis() - start < 2000) {
+    GPS.read();
+    if (GPS.newNMEAreceived()) {
+      GPS.lastNMEA();
+    }
+  }
+
   // the nice thing about this code is you can have a timer0 interrupt go off
   // every 1 millisecond, and read data from the GPS for you. that makes the
   // loop code a heck of a lot easier!