diff --git a/.travis.yml b/.travis.yml
index 608149812c5..7f534572ed5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -31,7 +31,9 @@ script:
 
 env:
   matrix:
-    - PYTHONASYNCIODEBUG=1 AIOHTTP_NO_EXTENSIONS=0
-    - PYTHONASYNCIODEBUG=0 AIOHTTP_NO_EXTENSIONS=0
-    - PYTHONASYNCIODEBUG=1 AIOHTTP_NO_EXTENSIONS=1
-    - PYTHONASYNCIODEBUG=0 AIOHTTP_NO_EXTENSIONS=1
+    # PYTHONASYNCIODEBUG and AIOHTTP_NO_EXTENSIONS environment variables
+    # are considered as enabled if they are any non empty strings.
+    - PYTHONASYNCIODEBUG=X AIOHTTP_NO_EXTENSIONS=
+    - PYTHONASYNCIODEBUG=  AIOHTTP_NO_EXTENSIONS=
+    - PYTHONASYNCIODEBUG=X AIOHTTP_NO_EXTENSIONS=X
+    - PYTHONASYNCIODEBUG=  AIOHTTP_NO_EXTENSIONS=X