diff --git a/src/cmd/go/alldocs.go b/src/cmd/go/alldocs.go
index ced43b6d5bb853..f227d93de70b7d 100644
--- a/src/cmd/go/alldocs.go
+++ b/src/cmd/go/alldocs.go
@@ -2210,7 +2210,10 @@
 //		Build the listed main package, plus all packages it imports,
 //		into a C shared library. The only callable symbols will
 //		be those functions exported using a cgo //export comment.
-//		Requires exactly one main package to be listed.
+//		On wasip1, this mode builds it to a WASI reactor/library,
+//		of which the callable symbols are those functions exported
+//		using a //go:wasmexport directive. Requires exactly one
+//		main package to be listed.
 //
 //	-buildmode=default
 //		Listed main packages are built into executables and listed
diff --git a/src/cmd/go/internal/help/helpdoc.go b/src/cmd/go/internal/help/helpdoc.go
index a64f980e5ee610..d373c675f66886 100644
--- a/src/cmd/go/internal/help/helpdoc.go
+++ b/src/cmd/go/internal/help/helpdoc.go
@@ -769,7 +769,10 @@ are:
 		Build the listed main package, plus all packages it imports,
 		into a C shared library. The only callable symbols will
 		be those functions exported using a cgo //export comment.
-		Requires exactly one main package to be listed.
+		On wasip1, this mode builds it to a WASI reactor/library,
+		of which the callable symbols are those functions exported
+		using a //go:wasmexport directive. Requires exactly one
+		main package to be listed.
 
 	-buildmode=default
 		Listed main packages are built into executables and listed