diff --git a/lib/helpers.js b/lib/helpers.js
index b5f7342..53eb715 100644
--- a/lib/helpers.js
+++ b/lib/helpers.js
@@ -388,7 +388,9 @@ function parse(data, regex) {
   }
 
   const options = assign({ flags: '' }, opts);
-  options.flags += 'g';
+  if (options.flags.indexOf('g') === -1) {
+    options.flags += 'g';
+  }
 
   const messages = [];
   const compiledRegexp = NamedRegexp(regex, options.flags);
diff --git a/src/helpers.js b/src/helpers.js
index be6e2ae..21ad5a0 100644
--- a/src/helpers.js
+++ b/src/helpers.js
@@ -332,7 +332,9 @@ export function parse(data, regex, opts = {}) {
   }
 
   const options = assign({flags: ''}, opts)
-  options.flags += 'g'
+  if (options.flags.indexOf('g') === -1) {
+    options.flags += 'g'
+  }
 
   const messages = []
   const compiledRegexp = NamedRegexp(regex, options.flags)