diff --git a/repo/project.py b/repo/project.py
index 8087352..d4a6130 100644
--- a/repo/project.py
+++ b/repo/project.py
@@ -3952,14 +3952,17 @@ def _ConfigureDepth(self, depth):
     """
     # Opt.depth will be non-None if user actually passed --depth to repo init.
     if depth is not None:
-      if depth > 0:
-        # Positive values will set the depth.
-        depth = str(depth)
-      else:
-        # Negative numbers will clear the depth; passing None to SetString
-        # will do that.
-        depth = None
-
+      try:
+        if int(depth) > 0:
+          # Positive values will set the depth.
+          depth = str(depth)
+        else:
+          # Negative numbers will clear the depth; passing None to SetString
+          # will do that.
+          depth = None
+      except ValueError:
+                depth = None
+                _warn("depth: invalid integer value: '%s'", depth)
       # We store the depth in the main manifest project.
       self.config.SetString('repo.depth', depth)