diff --git a/CMakeLists.txt b/CMakeLists.txt
index 78030d1622..6ce71b4e72 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -25,7 +25,11 @@ message(STATUS "Using compiler ${CMAKE_CXX_COMPILER_ID} ${CMAKE_CXX_COMPILER_VER
 option(UNITY_DISABLE "Disable unity build" OFF)
 if (NOT UNITY_DISABLE AND NOT DEFINED ENV{UNITY_DISABLE})
   set(CMAKE_UNITY_BUILD ON)
-  set(CMAKE_UNITY_BUILD_BATCH_SIZE 50)
+  if (DEFINED ENV{UNITY_BUILD_BATCH_SIZE})
+    set(CMAKE_UNITY_BUILD_BATCH_SIZE $ENV{UNITY_BUILD_BATCH_SIZE})
+  else()
+    set(CMAKE_UNITY_BUILD_BATCH_SIZE 50)
+  endif()
   message(STATUS "Using Unity Build with batch ${CMAKE_UNITY_BUILD_BATCH_SIZE}, export UNITY_DISABLE=1 or use -DUNITY_DISABLE=ON to disable it.")
 endif()