diff --git a/cmd/codegen/presets.go b/cmd/codegen/presets.go
index b3df45dc..5b61ae6b 100644
--- a/cmd/codegen/presets.go
+++ b/cmd/codegen/presets.go
@@ -1,5 +1,7 @@
 package main
 
+import "strings"
+
 // Preset is a set of rules iperative to XXX_templates/ json files.
 // They are used to manually set some properties of the generator.
 type Preset struct {
@@ -55,5 +57,7 @@ func (p *Preset) MergeCGoPreamble() string {
 		result += "// " + line + "\n"
 	}
 
+	result = strings.TrimSuffix(result, "\n")
+
 	return result
 }