diff --git a/CMakeLists.txt b/CMakeLists.txt
index bdf3fdc40..2ab58fae6 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -153,7 +153,11 @@ if(FSFW_BUILD_TESTS)
       "${MSG_PREFIX} Building the FSFW unittests in addition to the static library"
   )
   # Check whether the user has already installed Catch2 first
+  # Suppress this check for rtems, because rtems is cross compiled
+  # on CI with preinstalled Catch which needs to be cross compiled
+  if(NOT FSFW_OSAL MATCHES "rtems")
   find_package(Catch2 ${FSFW_CATCH2_LIB_MAJOR_VERSION})
+  endif()
   # Not installed, so use FetchContent to download and provide Catch2
   if(NOT Catch2_FOUND)
     message(
@@ -217,7 +221,11 @@ message(
 )
 
 # Check whether the user has already installed ETL first
+# Suppress this check for rtems, because rtems is cross compiled
+# on CI with preinstalled etl which is not found when cross compiling
+if(NOT FSFW_OSAL MATCHES "rtems")
 find_package(${FSFW_ETL_LIB_NAME} ${FSFW_ETL_LIB_MAJOR_VERSION} QUIET)
+endif()
 # Not installed, so use FetchContent to download and provide etl
 if(NOT ${FSFW_ETL_LIB_NAME}_FOUND)
   message(