diff --git a/mozci/platforms.py b/mozci/platforms.py
index 16ca3f4..4c40593 100755
--- a/mozci/platforms.py
+++ b/mozci/platforms.py
@@ -326,7 +326,7 @@ def _get_job_type(test_job):
 
 def build_tests_per_platform_graph(builders):
     """Return a graph mapping platforms to tests that run in it."""
-    graph = {'debug': {}, 'opt': {}}
+    graph = {'debug': {}, 'opt': {}, 'pgo': {}}
     up_builders = []
     dn_builders = []