diff --git a/README.md b/README.md
index d8ad23f12ba9f7d5042ae6e980e2b7d8efed1a87..ffc25dc6d83aa284a2dba9bbaa101e3c0455cd74 100644
--- a/README.md
+++ b/README.md
@@ -12,6 +12,8 @@ snakehouse
 snakehouse is a tool to pack mutiple .pyx files
 into a single extension.
 
+_There's a **MANDATORY READING** part at the end of this README. Read it or you will be sure to run into trouble._
+
 Inspired by [this StackOverflow discussion](https://stackoverflow.com/questions/30157363/collapse-multiple-submodules-to-one-cython-extension).
 
 Tested and works on CPython 3.5-3.9, 
@@ -24,8 +26,8 @@ a part of your pull request as well!
 Note what have you changed in
 [CHANGELOG.md](/CHANGELOG.md) as well!
 
-Usage notes
------------
+Usage notes - MANDATORY READING
+-------------------------------
 Take a look at [example](example/) on how to multi-build your Cython extensions.
 
 Don't place modules compiled that way in root .py file's top level imports.
@@ -38,3 +40,22 @@ the built module has a tendency to dump core.
 Try to debug it first by passing `dont_snakehouse=True` to your
 modules in the debug mode.
 
+Also note that if you are compiling in `dont_snakehouse`
+mode then your modules should have at least one of the following:
+* a normal Python `def`
+* a normal Python class (not `cdef class`)
+* a line of Python initialization, eg.
+
+```python
+a = None
+```
+
+or 
+```python
+import logging
+
+logger = logging.getLogger(__name__)
+```
+
+Otherwise `PyInit` won't be generated by Cython 
+and such module will be unimportable in Python. Normal import won't suffice.