diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 8a74c6b..cc68663 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -48,6 +48,10 @@
 
     add_executable(test_suite_${data_name} test_suite_${data_name}.c $<TARGET_OBJECTS:mbedtls_test>)
     target_link_libraries(test_suite_${data_name} ${libs})
+    # Include test-specific header files from ./include and private header
+    # files (used by some invasive tests) from ../library. Public header
+    # files are automatically included because the library targets declare
+    # them as PUBLIC.
     target_include_directories(test_suite_${data_name}
         PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/include
         PRIVATE ${CMAKE_CURRENT_SOURCE_DIR}/../library)
diff --git a/tests/Makefile b/tests/Makefile
index 80c84fa..ffa4812 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -6,6 +6,9 @@
 WARNING_CFLAGS ?= -Wall -Wextra
 LDFLAGS ?=
 
+# Include public header files from ../include, test-specific header files
+# from ./include, and private header files (used by some invasive tests)
+# from ../library.
 LOCAL_CFLAGS = $(WARNING_CFLAGS) -I./include -I../include -I../library -D_FILE_OFFSET_BITS=64
 LOCAL_LDFLAGS = -L../library			\
 		-lmbedtls$(SHARED_SUFFIX)	\