prompted by #27693
diff --git a/cgo.md b/cgo.md
index 624576f..b0df901 100644
--- a/cgo.md
+++ b/cgo.md
@@ -324,4 +324,10 @@
### Windows
-In order to use cgo on Windows, you'll also need to first install a gcc compiler (for instance, mingw-w64) and have gcc.exe (etc.) in your PATH environment variable before compiling with cgo will work.
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+In order to use cgo on Windows, you'll also need to first install a gcc compiler (for instance, mingw-w64) and have gcc.exe (etc.) in your PATH environment variable before compiling with cgo will work.
+
+### environmental variables
+Go doesn't see variables set by C.setenv
+
+### tests
+_test.go files can't use cgo.
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