diff --git a/test/encode_test_driver.cc b/test/encode_test_driver.cc
index d40256a..ce7e5b3 100644
--- a/test/encode_test_driver.cc
+++ b/test/encode_test_driver.cc
@@ -94,6 +94,8 @@
 
 void EncoderTest::RunLoop(VideoSource *video) {
   for (unsigned int pass = 0; pass < passes_; pass++) {
+    last_pts_ = 0;
+
     if (passes_ == 1)
       cfg_.g_pass = VPX_RC_ONE_PASS;
     else if (pass == 0)
@@ -120,6 +122,8 @@
         if (pkt->kind != VPX_CODEC_CX_FRAME_PKT)
           continue;
 
+        ASSERT_GE(pkt->data.frame.pts, last_pts_);
+        last_pts_ = pkt->data.frame.pts;
         FramePktHook(pkt);
       }
 
diff --git a/test/encode_test_driver.h b/test/encode_test_driver.h
index f00fe3c..d9a79ec 100644
--- a/test/encode_test_driver.h
+++ b/test/encode_test_driver.h
@@ -138,7 +138,7 @@
 // classes directly, so that tests can be parameterized differently.
 class EncoderTest {
  protected:
-  EncoderTest() : abort_(false), flags_(0) {}
+  EncoderTest() : abort_(false), flags_(0), last_pts_(0) {}
 
   virtual ~EncoderTest() {}
 
@@ -177,6 +177,7 @@
   unsigned long        deadline_;
   TwopassStatsStore    stats_;
   unsigned long        flags_;
+  vpx_codec_pts_t      last_pts_;
 };
 
 }  // namespace libvpx_test