diff --git a/platformio.ini b/platformio.ini
index e8b1728b..637e06af 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -200,7 +200,7 @@ upload_speed = 115200
 lib_compat_mode = strict
 lib_deps =
     ;fastled/FastLED @ 3.5.0
-    https://github.com/FastLED/FastLED.git#master ;; up to 50% faster
+    https://github.com/FastLED/FastLED.git#master @3.5.0+sha.3d2ab78 ;; up to 50% faster - using a "known good" hash, so we get predictable builds
     IRremoteESP8266 @ 2.8.2
     ;;https://github.com/Aircoookie/ESPAsyncWebServer.git @ ~2.0.7
     https://github.com/lost-hope/ESPAsyncWebServer.git#master  ;; WLEDMM to display .log and .wled files in /edit