diff --git a/src/bin/wasmtime.rs b/src/bin/wasmtime.rs
index e16724e9bb..10e362ea95 100644
--- a/src/bin/wasmtime.rs
+++ b/src/bin/wasmtime.rs
@@ -278,7 +278,7 @@ fn rmain() -> Result<(), Error> {
 
     // Enable optimization if requested.
     if args.flag_optimize {
-        flag_builder.set("opt_level", "best")?;
+        flag_builder.set("opt_level", "speed")?;
     }
 
     let config = Config::new(settings::Flags::new(flag_builder), features, debug_info);