diff --git a/CMakeLists.txt b/CMakeLists.txt
index 0b58c07b..96304e2f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -116,6 +116,8 @@ ExternalProject_Add(RegsGen2
     -DCMAKE_BUILD_TYPE:STRING=Release
     -DCMAKE_SYSTEM_NAME:STRING=${CMAKE_HOST_SYSTEM_NAME}
     -DCMAKE_SYSTEM_PROCESSOR:STRING=${CMAKE_HOST_SYSTEM_PROCESSOR}
+    -DBISON_EXECUTABLE=${BISON_EXECUTABLE}
+    -DFLEX_EXECUTABLE=${FLEX_EXECUTABLE}
   BUILD_COMMAND ${CMAKE_COMMAND} --build <BINARY_DIR> --config Release
   INSTALL_COMMAND ""
   BUILD_BYPRODUCTS