diff --git a/libc/test/UnitTest/CMakeLists.txt b/libc/test/UnitTest/CMakeLists.txt
--- a/libc/test/UnitTest/CMakeLists.txt
+++ b/libc/test/UnitTest/CMakeLists.txt
@@ -26,6 +26,9 @@
 
 foreach(lib LibcUnitTest LibcHermeticTest)
   target_include_directories(${lib} PUBLIC ${LIBC_SOURCE_DIR})
+  if(LIBC_ENABLE_HERMETIC_TESTS AND NOT LIBC_ENABLE_UNITTESTS)
+    target_include_directories(${lib} PRIVATE ${LIBC_BUILD_DIR}/include)
+  endif()
   target_compile_options(${lib} PRIVATE ${LIBC_HERMETIC_TEST_COMPILE_OPTIONS}
                          -fno-exceptions -fno-rtti)
   add_dependencies(${lib}
@@ -37,6 +40,7 @@
   )
 endforeach()
 
+target_include_directories(LibcHermeticTest PRIVATE ${LIBC_BUILD_DIR}/include)
 target_compile_options(LibcHermeticTest PRIVATE -ffreestanding -nostdlib -nostdlib++)
 
 add_library(