diff --git a/CMakeLists.txt b/CMakeLists.txt
index 93835ef83e..d6999eb1d9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -19,6 +19,12 @@ if(POLICY CMP0077)
   cmake_policy(SET CMP0077 NEW)
 endif()
 
+# CMP0116: Ninja generators transform `DEPFILE`s from `add_custom_command()`
+# New in CMake 3.20. https://cmake.org/cmake/help/latest/policy/CMP0116.html
+if(POLICY CMP0116)
+  cmake_policy(SET CMP0116 OLD)
+endif()
+
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED YES)
 
@@ -38,11 +44,11 @@ if( CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR )
 # Project setup and globals
 #-------------------------------------------------------------------------------
   project(circt LANGUAGES CXX C)
-  
+
 #-------------------------------------------------------------------------------
 # Options and settings
 #-------------------------------------------------------------------------------
-  
+
   option(LLVM_INCLUDE_TOOLS "Generate build targets for the LLVM tools." ON)
   option(LLVM_BUILD_TOOLS "Build the LLVM tools. If OFF, just generate build targets." ON)
 
@@ -51,22 +57,22 @@ if (MSVC)
 else ()
   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fno-exceptions -fno-rtti")
 endif ()
-  
+
 #-------------------------------------------------------------------------------
 # MLIR/LLVM Configuration
 #-------------------------------------------------------------------------------
-  
+
   find_package(MLIR REQUIRED CONFIG)
-  
+
   message(STATUS "Using MLIRConfig.cmake in: ${MLIR_DIR}")
   message(STATUS "Using LLVMConfig.cmake in: ${LLVM_DIR}")
-  
+
   set(LLVM_RUNTIME_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/bin)
   set(LLVM_LIBRARY_OUTPUT_INTDIR ${CMAKE_BINARY_DIR}/lib)
-  
+
   list(APPEND CMAKE_MODULE_PATH "${MLIR_CMAKE_DIR}")
   list(APPEND CMAKE_MODULE_PATH "${LLVM_CMAKE_DIR}")
-  
+
   include(TableGen)
   include(AddLLVM)
   include(AddMLIR)