diff --git a/viper.go b/viper.go
index 2f82f91..dc25114 100644
--- a/viper.go
+++ b/viper.go
@@ -1191,6 +1191,9 @@ func parseStringToStringFlagValue(val string) map[string]string {
 	result := make(map[string]string, len(elements))
 	for _, element := range elements {
 		pair := strings.SplitN(element, "=", 2)
+		if len(pair) != 2 {
+			return nil
+		}
 		result[pair[0]] = pair[1]
 	}
 	return result