diff --git a/src/HDF5.jl b/src/HDF5.jl
index 566fd663b..d505a32e0 100644
--- a/src/HDF5.jl
+++ b/src/HDF5.jl
@@ -1,5 +1,9 @@
 module HDF5
 
+if isdefined(Base, :Experimental) && isdefined(Base.Experimental, Symbol("@optlevel"))
+    @eval Base.Experimental.@optlevel 1
+end
+
 using Base: unsafe_convert
 using Requires: @require
 # needed for filter(f, tuple) in julia 1.3