diff --git a/3.3.5a/include/tempest/rect.h b/3.3.5a/include/tempest/rect.h
index 01e1ccd..869df5a 100644
--- a/3.3.5a/include/tempest/rect.h
+++ b/3.3.5a/include/tempest/rect.h
@@ -3,6 +3,9 @@
 
 #include <stdint.h>
 
+typedef struct CRect CRect;
+typedef struct CiRect CiRect;
+
 struct CRect {
   float minY; // t
   float minX; // l
diff --git a/3.3.5a/include/tempest/sphere.h b/3.3.5a/include/tempest/sphere.h
index 729c63b..24f7983 100644
--- a/3.3.5a/include/tempest/sphere.h
+++ b/3.3.5a/include/tempest/sphere.h
@@ -3,6 +3,8 @@
 
 #include "tempest/vector.h"
 
+typedef struct CAaSphere CAaSphere;
+
 struct CAaSphere {
   C3Vector n;
   float d;
diff --git a/3.3.5a/symbol/gx/func.sym b/3.3.5a/symbol/gx/func.sym
new file mode 100644
index 0000000..4fecf61
--- /dev/null
+++ b/3.3.5a/symbol/gx/func.sym
@@ -0,0 +1,13 @@
+GxDevApi 00682d20 f
+GxDrawLockedElements 00682340 f
+GxLog 006817e0 f
+GxPrimIndexPtr 00681ab0 f
+GxPrimLockVertexPtrs 006828c0 f
+GxPrimVertexPtr_FFP 00682400 f ; this is one of the functions named 'GxPrimVertexPtr' that uses the fixed-function pipeline
+GxuDetermineQuotedCode 006bd5a0 f
+GxuFontAddToBatch 006bce10 f
+GxuFontCreateString 006be2b0 f
+GxuFontDestroyString 006bdfc0 f
+GxuFontGetMaxCharsWithinWidth 006bcea0 f
+GxuFontGetTextExtent 006bce60 f
+GxuFontSetStringPosition 006bd0a0 f
\ No newline at end of file
diff --git a/3.3.5a/symbol/main.sym b/3.3.5a/symbol/main.sym
new file mode 100644
index 0000000..e69de29
diff --git a/README.md b/README.md
index cf4c356..145ce01 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,18 @@ You can use the information here to get a headstart when working on the [Whoa pr
 
 To make reverse engineering easier, C header files matching the original memory layout are provided.
 
-The header `<game version>/include/main.h` to import type definitions into your analysis repository.
+## Importing headers
+
+To use these headers in Ghidra,
+
+  1. go to `File` > `Parse C Source...`. 
+  2. Select `clib.prf` as your parse configuration, and clear all source files and input paths.
+  3. Add the header `<game version>/include/main.h` to the `Source files to parse` combo box.
+  4. press `Parse to Program`.
+
+TODO: equivalent guide for IDA Pro.
+
+## Maintaining headers
 
 Headers should be restricted at all times to the C programming language only. C++ syntax will break type analysis.
 
@@ -23,3 +34,7 @@ should become:
 ```c
 void Name__Space__Thing();
 ```
+
+# Symbol files
+
+Symbol files are text files that map function names and data labels to addresses. 
\ No newline at end of file