diff --git a/modules/audio_coding/neteq/tools/neteq_quality_test.cc b/modules/audio_coding/neteq/tools/neteq_quality_test.cc
index 54d8bbbe92..81305efe27 100644
--- a/modules/audio_coding/neteq/tools/neteq_quality_test.cc
+++ b/modules/audio_coding/neteq/tools/neteq_quality_test.cc
@@ -38,8 +38,13 @@ const std::string& DefaultOutFilename() {
 }
 
 // Common validator for file names.
-static bool ValidateFilename(const std::string& value, bool write) {
-  FILE* fid = write ? fopen(value.c_str(), "wb") : fopen(value.c_str(), "rb");
+static bool ValidateFilename(const std::string& value, bool is_output) {
+  if (!is_output) {
+    RTC_CHECK_NE(value.substr(value.find_last_of(".") + 1), "wav")
+        << "WAV file input is not supported";
+  }
+  FILE* fid =
+      is_output ? fopen(value.c_str(), "wb") : fopen(value.c_str(), "rb");
   if (fid == nullptr)
     return false;
   fclose(fid);