diff --git a/README.md b/README.md
index 724ba54..9381fb1 100644
--- a/README.md
+++ b/README.md
@@ -1,15 +1,12 @@
 # libvieter
 
-This library powers part of Vieter, most noteably the sections that can easily
+This library powers part of Vieter, most notably the sections that can easily
 be implemented in C (or just parts I want to implement in C because it's fun).
 
-The goal of this library is to be completely self-contained, meaning any
-required data structures have to be implemented as well. It can only depend on
-the C standard libraries.
+The goal of this library is to be as self-contained as possible; data
+structures should be implemented manually if possible.
 
-Currently it contains the following:
-
-* Cron expression parser & next time calculator
+See the [source code](/src) for the list of modules.
 
 ## Development
 
@@ -18,6 +15,27 @@ Currently it contains the following:
 Everything is handled by the provided Makefile. To compile the static library,
 simply run `make`.
 
+### Project structure
+
+Each module has its own subdirectory inside `src`, e.g. `src/cron`. This
+directory contains the actual implementation of a module, along with any
+internally used header files. Each internal function should be defined in a
+header file, as to make testing these possible.
+
+Each module should also have its own header file inside the `include`
+directory. This header file defines the public API that the library exposes for
+this specific module.
+
+Any code in a module may only import internal headers from that module, along
+with any of the public API header files. Modules should not depend on each
+other's internal implementationns.
+
+Each module should contain a README describing its contents.
+
+All file names, function names... (even internals) should follow snake case
+convention and have a prefix unique to that module, starting with `vieter_`.
+For example, the `cron` modules uses the `vieter_cron_` prefix for everything.
+
 ### Testing
 
 This library uses [Acutest](https://github.com/mity/acutest) for its tests.
@@ -25,6 +43,10 @@ Tests should be placed in the `test` subdirectory, further divided into
 directories that correspond those in `src`. Test files should begin with
 `test_`, and their format should follow the expected format for Acutest.
 
+Each `test_` is compiled separately into a binary, linked with libvieter. A
+test file can import any of the public API header files, along with any header
+files defined in its respective module. This allows testing internal functions.
+
 To run the tests, simply run `make test`. If you wish to only run a specific
 test binary, you can find them in `build/test`.
 
diff --git a/src/cron/expression.c b/src/cron/vieter_cron_expression.c
similarity index 100%
rename from src/cron/expression.c
rename to src/cron/vieter_cron_expression.c
diff --git a/src/cron/parse.c b/src/cron/vieter_cron_parse.c
similarity index 100%
rename from src/cron/parse.c
rename to src/cron/vieter_cron_parse.c
diff --git a/src/heap/vieter_heap_tree.h b/src/heap/vieter_heap_tree.h
index 73e1611..18808e1 100644
--- a/src/heap/vieter_heap_tree.h
+++ b/src/heap/vieter_heap_tree.h
@@ -15,7 +15,7 @@ vieter_heap_node *vieter_heap_node_init();
 
 void vieter_heap_node_free(vieter_heap_node *node);
 
-vieter_heap_node *vieter_heap_node_merge_same_order(vieter_heap_node *root_a, vieter_heap_node *root_b);
+vieter_heap_node *vieter_heap_tree_merge_same_order(vieter_heap_node *root_a, vieter_heap_node *root_b);
 
 typedef struct vieter_heap_tree {
     uint64_t order;