diff --git a/response.go b/response.go
index e1f494b..5414578 100644
--- a/response.go
+++ b/response.go
@@ -111,6 +111,8 @@ type FakeResponse struct {
 
 // Returns true either when nothing to compare or deep equal check passed
 func (fr *FakeResponse) isArgsMatch(args []driver.NamedValue) bool {
+	fr.mu.Lock()
+	defer fr.mu.Unlock()
 	arguments := make([]interface{}, len(args))
 	if len(args) > 0 {
 		for index, arg := range args {
@@ -121,14 +123,19 @@ func (fr *FakeResponse) isArgsMatch(args []driver.NamedValue) bool {
 }
 
 func (fr *FakeResponse) isQueryMatch(query string) bool {
+	fr.mu.Lock()
+	defer fr.mu.Unlock()
 	return fr.Pattern == "" || strings.Contains(query, fr.Pattern)
 }
 
 // IsMatch checks if both query and args matcher's return true and if this is Once mock
 func (fr *FakeResponse) IsMatch(query string, args []driver.NamedValue) bool {
+	fr.mu.Lock()
 	if fr.Once && fr.Triggered {
+		fr.mu.Unlock()
 		return false
 	}
+	fr.mu.Unlock()
 	return fr.isQueryMatch(query) && fr.isArgsMatch(args)
 }