diff --git a/coreos_prometheus/Tiltfile b/coreos_prometheus/Tiltfile
index b46c5c586..1ba6bf46e 100644
--- a/coreos_prometheus/Tiltfile
+++ b/coreos_prometheus/Tiltfile
@@ -3,13 +3,15 @@
 def _find_root_tiltfile_dir():
     # Find top-level Tilt path
     current = os.path.abspath('./')
-    while current != '/':
-        if os.path.exists(os.path.join(current, 'Tiltfile')):
+    while True:
+        if os.path.exists(os.path.join(current, 'tilt_modules')):
             return current
 
-        current = os.path.dirname(current)
+        next_dir = os.path.dirname(current)
+        if next_dir == current:
+            fail('Could not find root Tiltfile')
 
-    fail('Could not find root Tiltfile')
+        current = next_dir
 
 def _find_cache_dir():
     cachedir = os.getenv('TILT_CACHE_DIR', '')
diff --git a/git_resource/Tiltfile b/git_resource/Tiltfile
index 8224878a7..10b7443f8 100644
--- a/git_resource/Tiltfile
+++ b/git_resource/Tiltfile
@@ -2,13 +2,15 @@
 def _find_root_tiltfile_dir():
     # Find top-level Tilt path
     current = os.path.abspath('./')
-    while current != '/':
+    while True:
         if os.path.exists(os.path.join(current, 'tilt_modules')):
             return current
 
-        current = os.path.dirname(current)
+        next_dir = os.path.dirname(current)
+        if next_dir == current:
+            fail('Could not find root Tiltfile')
 
-    fail('Could not find root Tiltfile')
+        current = next_dir
 
 def _find_checkout_dir():
     from_env = os.getenv('TILT_GIT_RESOURCE_CHECKOUT_DIR', '')
diff --git a/helm_remote/Tiltfile b/helm_remote/Tiltfile
index 38ad57ec2..9857383e9 100644
--- a/helm_remote/Tiltfile
+++ b/helm_remote/Tiltfile
@@ -19,13 +19,15 @@ if _get_skip() == None:
 def _find_root_tiltfile_dir():
     # Find top-level Tilt path
     current = os.path.abspath('./')
-    while current != '/':
+    while True:
         if os.path.exists(os.path.join(current, 'tilt_modules')):
             return current
 
-        current = os.path.dirname(current)
+        next_dir = os.path.dirname(current)
+        if next_dir == current:
+            fail('Could not find root Tiltfile')
 
-    fail('Could not find root Tiltfile')
+        current = next_dir
 
 def _find_cache_dir():
     from_env = os.getenv('TILT_HELM_REMOTE_CACHE_DIR', '')