diff --git a/build.py b/build.py
index d6d8827bb..8b78ec548 100755
--- a/build.py
+++ b/build.py
@@ -1,4 +1,9 @@
 #!/usr/bin/python2.7
+#
+# Deprecation warning: (July 2020)
+# This build script has been deprecated, please use 'npm run build' instead.
+# The script will be removed from Blockly core in Q4 of 2020.
+#
 # Compresses the core Blockly files into a single JavaScript file.
 #
 # Copyright 2012 Google LLC
@@ -485,9 +490,9 @@ if __name__ == "__main__":
   full_search_paths = calcdeps.ExpandDirectories(["core", "closure"])
   full_search_paths = sorted(full_search_paths)  # Deterministic build.
 
-  print("Deprecation Warning: \n This build script has been deprecated, " +
-    "please use 'npm run build' instead. \n The script will be removed from " +
-    "Blockly core in Q4 of 2020.\n")
+  print("Deprecation Warning: (July 2020)\n This build script has been " +
+    "deprecated, please use 'npm run build' instead. \n The script will be " +
+    "removed from Blockly core in Q4 of 2020.\n")
 
   # Uncompressed and compressed are run in parallel threads.
   # Uncompressed is limited by processor speed.