diff --git a/cmake/ExperimentalFeatures.cmake b/cmake/ExperimentalFeatures.cmake
index 57a66e68d..7eff40bdb 100644
--- a/cmake/ExperimentalFeatures.cmake
+++ b/cmake/ExperimentalFeatures.cmake
@@ -13,7 +13,7 @@ if(EXPERIMENTAL_SHA256)
 
 	set(EXPERIMENTAL 1)
 	set(GIT_EXPERIMENTAL_SHA256 1)
-	add_compile_definitions(GIT_EXPERIMENTAL_SHA256)
+	add_definitions(-DGIT_EXPERIMENTAL_SHA256=1)
 else()
 	add_feature_info("SHA256 API" OFF "experimental SHA256 APIs")
 endif()