diff --git a/Modules/Compiler/IAR-C.cmake b/Modules/Compiler/IAR-C.cmake
index 48a9a16890..55e019ec7f 100644
--- a/Modules/Compiler/IAR-C.cmake
+++ b/Modules/Compiler/IAR-C.cmake
@@ -5,6 +5,9 @@ include(Compiler/CMakeCommonCompilerMacros)
 
 # The toolchains for ARM and AVR are quite different:
 if("${CMAKE_C_COMPILER_ARCHITECTURE_ID}" STREQUAL "ARM")
+
+  set(CMAKE_C_EXTENSION_COMPILE_OPTION -e)
+
   set(CMAKE_C90_STANDARD_COMPILE_OPTION "")
   set(CMAKE_C90_EXTENSION_COMPILE_OPTION -e)
 
diff --git a/Modules/Compiler/IAR-CXX.cmake b/Modules/Compiler/IAR-CXX.cmake
index 7a6ba2b52b..8d86100a5e 100644
--- a/Modules/Compiler/IAR-CXX.cmake
+++ b/Modules/Compiler/IAR-CXX.cmake
@@ -17,6 +17,8 @@ if("${CMAKE_CXX_COMPILER_ARCHITECTURE_ID}" STREQUAL "ARM")
     endif()
   endif()
 
+  set(CMAKE_CXX_EXTENSION_COMPILE_OPTION -e)
+
   set(CMAKE_CXX98_STANDARD_COMPILE_OPTION "")
   set(CMAKE_CXX98_EXTENSION_COMPILE_OPTION -e)