diff --git a/README.md b/README.md
index a9a1e28..2981fff 100644
--- a/README.md
+++ b/README.md
@@ -14,7 +14,11 @@ wasi-i2c is currently in [Phase 1](https://github.com/WebAssembly/WASI/blob/main
 
 ### Portability Criteria
 
-WASI-I2C must have at least two complete independent implementations. One implementation must be implemented on a microcontroller.
+WASI-I2C must have at least an independent implementation for the following platforms: 
+- Linux (ARM)
+- Linux (RISC-V)
+- RTOS (Zephyr or FreeRTOS)
+- Microcontroller implementation (Cortex M4 as a lowerbound)
 
 ### Introduction