diff --git a/firmware/pch/readme.md b/firmware/pch/readme.md
index ad869ea48c..928ece2cb6 100644
--- a/firmware/pch/readme.md
+++ b/firmware/pch/readme.md
@@ -1,3 +1,5 @@
 This folder is about Precompiled Headers
 
-See rusefi_pch.mk
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+See rusefi_pch.mk
+
+Unfortunately only one pch per project https://stackoverflow.com/questions/2542483/can-i-use-multiple-pch-files-in-1-project
\ No newline at end of file