diff --git a/Makefile b/Makefile
index aebf6354..98ff2ede 100644
--- a/Makefile
+++ b/Makefile
@@ -391,6 +391,8 @@ endif
 	@$(MD5SUM) test.hex
 	$(TINYGO) build             -o test.nro -target=nintendoswitch      examples/serial
 	@$(MD5SUM) test.nro
+	$(TINYGO) build -size short -o test.hex -target=pca10040 -opt=0     ./testdata/stdlib.go
+	@$(MD5SUM) test.hex
 
 wasmtest:
 	$(GO) test ./tests/wasm
diff --git a/builder/build.go b/builder/build.go
index bdeccad5..e5977770 100644
--- a/builder/build.go
+++ b/builder/build.go
@@ -411,15 +411,8 @@ func compileWholeProgram(pkgName string, config *compileopts.Config, compilerCon
 	// exactly.
 	errs = nil
 	switch config.Options.Opt {
-	/*
-		Currently, turning optimizations off causes compile failures.
-		We rely on the optimizer removing some dead symbols.
-		Avoid providing an option that does not work right now.
-		In the future once everything has been fixed we can re-enable this.
-
-		case "none", "0":
-			errs = transform.Optimize(mod, config, 0, 0, 0) // -O0
-	*/
+	case "none", "0":
+		errs = transform.Optimize(mod, config, 0, 0, 0) // -O0
 	case "1":
 		errs = transform.Optimize(mod, config, 1, 0, 0) // -O1
 	case "2":
diff --git a/transform/optimizer.go b/transform/optimizer.go
index dc9e1ffb..e330d1af 100644
--- a/transform/optimizer.go
+++ b/transform/optimizer.go
@@ -111,6 +111,12 @@ func Optimize(mod llvm.Module, config *compileopts.Config, optLevel, sizeLevel i
 		if len(errs) > 0 {
 			return errs
 		}
+
+		// Clean up some leftover symbols of the previous transformations.
+		goPasses := llvm.NewPassManager()
+		defer goPasses.Dispose()
+		goPasses.AddGlobalDCEPass()
+		goPasses.Run(mod)
 	}
 
 	// Lower async implementations.