diff --git a/README.md b/README.md
index ebab861813caef8c16090e2d6976af74f76d4351..dd4a2a862e25217f14ab4890e9cf7396e4f116ee 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,7 @@
 |3.47|[pi.html](https://pub.pages.cba.mit.edu/pi/JavaScript/pi.html)|JavaScript, 1 worker|Intel 2x E5-2680|Nov 19, 2018|
 |3.29|[pi.js](Node/pi.js)|Node|Intel i7-8700T|Dec 8, 2018|
 |3.12|[clusterpi.js](Node/clusterpi.js)|Node, 1 worker|Intel i7-8700T|Dec 8, 2018|
+|1.78|[threadpi.c](C/threadpi.c)|C, 4 threads<br>gcc threadpi.c -o threadpi -O3 -ffast-math -pthread|Raspberry Pi 4|Dec 13, 2020|
 |0.57|[pi.c](C/pi.c)|C<br>gcc pi.c -o pi -lm|Intel i7-8700T|Nov 17, 2018|
 |0.47|[numpi.py](Python/numpi.py)|Python, NumPy|Intel i7-8700T|Nov 17, 2018|
 |0.029|[pi.py](Python/pi.py)|Python|Intel i7-8700T|Nov 17, 2018|