diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8d618ba..c601804 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -49,7 +49,10 @@ set(USB_ITF_CCID 1)
 set(USB_ITF_WCID 1)
 include(pico-keys-sdk/pico_keys_sdk_import.cmake)
 
-set(SOURCES ${PICO_KEYS_SOURCES}
+if(NOT ESP_PLATFORM)
+    set(SOURCES ${PICO_KEYS_SOURCES})
+endif()
+set(SOURCES ${SOURCES}
         ${CMAKE_CURRENT_LIST_DIR}/src/openpgp/openpgp.c
         ${CMAKE_CURRENT_LIST_DIR}/src/openpgp/files.c
         ${CMAKE_CURRENT_LIST_DIR}/src/openpgp/piv.c