diff --git a/prom.awk b/prom.awk
index 6a5ef39..fd61270 100644
--- a/prom.awk
+++ b/prom.awk
@@ -109,7 +109,7 @@ function _prom_assert_valid_label(name) {
 
 # Escape double quotes in label value VALUE and return the result.
 function _prom_label_escape(value) {
-  return gensub(/"/, /\"/, "g", value)
+  return gensub(/"/, "\\\\\"", "g", value)
 }