fix small error in -X usage
diff --git a/GcToolchainTricks.md b/GcToolchainTricks.md
index 72d98ee..50797a5 100644
--- a/GcToolchainTricks.md
+++ b/GcToolchainTricks.md
@@ -104,6 +104,6 @@
var BuildTime string
```
-You can build the program using this package using `go build -ldflags="-X 'company/buildinfo=$(date)'"` to record the build time in the string. (The use of `$(date)` assumes you are using a Unix-style shell.)
+You can build the program using this package using `go build -ldflags="-X 'company/buildinfo.BuildTime=$(date)'"` to record the build time in the string. (The use of `$(date)` assumes you are using a Unix-style shell.)
The string variable must exist, and it must be a variable, not a constant. There is no warning for using the wrong name in the `-X` option. You can often find the name to use by running `go tool nm` on the program, but that will fail if the package name has any non-ASCII characters, or a `"` or `%` character.
\ No newline at end of file
