diff --git a/CMakeLists.txt b/CMakeLists.txt
index 411801019..23addb268 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -421,6 +421,9 @@ elseif(CMAKE_C_COMPILER_ID MATCHES Clang)
     append_if_absent(CMAKE_C_FLAGS "-Wall")
     append_if_absent(CMAKE_C_FLAGS "-g")
 elseif(CMAKE_C_COMPILER_ID MATCHES Intel)
+    if(PY_VERSION VERSION_EQUAL "3.6" OR PY_VERSION VERSION_GREATER "3.6")
+        append_if_absent(CMAKE_C_FLAGS "-std=c99")
+    endif()
     append_if_absent(CMAKE_C_FLAGS "-Wall")
     append_if_absent(CMAKE_C_FLAGS "-no-ansi-alias")
 elseif(CMAKE_C_COMPILER_ID MATCHES PGI)