diff --git a/polly/tools/GPURuntime/CMakeLists.txt b/polly/tools/GPURuntime/CMakeLists.txt
index cc917020a190..4e17c276a11b 100644
--- a/polly/tools/GPURuntime/CMakeLists.txt
+++ b/polly/tools/GPURuntime/CMakeLists.txt
@@ -11,6 +11,8 @@ set_target_properties(GPURuntime
   PREFIX "lib"
   )
 
+set_property(TARGET GPURuntime PROPERTY C_STANDARD 99)
+
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fvisibility=default ")
 if ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fno-sanitize=all ")