diff --git a/gen/generator.go b/gen/generator.go
index 068cf73..4158c02 100644
--- a/gen/generator.go
+++ b/gen/generator.go
@@ -299,6 +299,7 @@ func camelToSnake(name string) string {
 
 	multipleUpper := false
 	var lastUpper rune
+	var beforeUpper rune
 
 	for _, c := range name {
 		// Non-lowercase character after uppercase is considered to be uppercase too.
@@ -312,7 +313,7 @@ func camelToSnake(name string) string {
 			firstInRow := !multipleUpper
 			lastInRow := !isUpper
 
-			if ret.Len() > 0 && (firstInRow || lastInRow) {
+			if ret.Len() > 0 && (firstInRow || lastInRow) && beforeUpper != '_' {
 				ret.WriteByte('_')
 			}
 			ret.WriteRune(unicode.ToLower(lastUpper))
@@ -328,6 +329,7 @@ func camelToSnake(name string) string {
 
 		ret.WriteRune(c)
 		lastUpper = 0
+		beforeUpper = c
 		multipleUpper = false
 	}