diff --git a/README.md b/README.md
index 16d217a..48c0a23 100644
--- a/README.md
+++ b/README.md
@@ -19,9 +19,13 @@ Implementations using the HAL are provided for the following interfaces:
 * SpiInterface, SpiDevice
 * UART
 
+To enable these implementations follow the instructions from the individual headers.
+
 
 # Atomic implementations
 
 Implementations using atomic variables are provided for the following interfaces:
 * Mutex
-* Signal
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+* Signal
+
+To enable these implementations define `STA_ATOMIC_ENABLE` in `<sta/config.hpp>`.
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