diff --git a/base/initdefs.jl b/base/initdefs.jl
index 97a67c88fe713..89ebecaefbdc4 100644
--- a/base/initdefs.jl
+++ b/base/initdefs.jl
@@ -315,6 +315,9 @@ end
     set_active_project(projfile::Union{AbstractString,Nothing})
 
 Set the active `Project.toml` file to `projfile`. See also [`Base.active_project`](@ref).
+
+!!! compat "Julia 1.8"
+    This function requires at least Julia 1.8.
 """
 function set_active_project(projfile::Union{AbstractString,Nothing})
     ACTIVE_PROJECT[] = projfile