diff --git a/AGENTS.md b/AGENTS.md
index 86b0f3aa3f..812e758400 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -111,8 +111,10 @@ python test.py -g --graphics=software
   around a hundred failures that mean nothing is wrong. The only meaningful result is `0 tests failed`.
   (The debug-CRT "Detected memory leaks!" dump after the summary line is normal, not a failure.)
 
-New unit tests are added to `availableTests`; large ones go in their own file in `unittest/`, listed in
-both CMakeLists.txt and the Visual Studio project.
+New unit tests are added to `availableTests`; large ones go in their own file in `unittest/`, which has
+to be listed in **three** build files, not two: `CMakeLists.txt`, `unittest/UnitTests.vcxproj` (and its
+`.filters`), and `android/jni/Android.mk`, which builds a unit test executable of its own. Miss the last
+one and it builds everywhere you can easily try it, and fails on Android CI.
 
 ## Multiplatform considerations
 
diff --git a/android/jni/Android.mk b/android/jni/Android.mk
index 63cff285ec..2e0a7ab5a9 100644
--- a/android/jni/Android.mk
+++ b/android/jni/Android.mk
@@ -1060,6 +1060,7 @@ ifeq ($(UNITTEST),1)
     $(SRC)/unittest/TestVFS.cpp \
     $(SRC)/unittest/TestDemangle.cpp \
     $(SRC)/unittest/TestLzrc.cpp \
+    $(SRC)/unittest/TestMpegCsc.cpp \
     $(SRC)/unittest/TestZipSlip.cpp \
     $(SRC)/unittest/UnitTest.cpp
 
diff --git a/docs/building.md b/docs/building.md
index e7a3c40300..f0a06c7258 100644
--- a/docs/building.md
+++ b/docs/building.md
@@ -128,7 +128,10 @@ main functions (and also stub out most of the System_ functions as needed). Take
 when making cross platform changes.
 
 New unit tests are added by listing them in availableTests in unittest.cpp. If they are large, put them in
-separate files in the unittest subdirectory. Remember to update both CMakeLists.txt and the visual studio project.
+separate files in the unittest subdirectory. A new file has to be listed in three build files, not two:
+`CMakeLists.txt`, `unittest/UnitTests.vcxproj` (and its `.filters`), and `android/jni/Android.mk`, which
+builds a unit test executable of its own. The Android one is the easiest to forget, since missing it builds
+fine everywhere you are likely to try it and only fails on Android CI.
 
 A unit test is often the first thing to call a given function from outside its own .cpp, which makes the
 `ppsspp_unittest` target in the legacy Android build (`android/jni/Android.mk`, see above) the strictest check