diff --git a/defs.bzl b/defs.bzl
index d618725eb8..7c89a05aea 100644
--- a/defs.bzl
+++ b/defs.bzl
@@ -80,7 +80,7 @@ def codex_rust_crate(
             `CARGO_BIN_EXE_*` environment variables. These are only needed for binaries from a different crate.
     """
     test_env = {
-        "INSTA_WORKSPACE_ROOT": ".",
+        "INSTA_WORKSPACE_ROOT": "codex-rs",
         "INSTA_SNAPSHOT_PATH": "src",
     }
 
@@ -127,7 +127,9 @@ def codex_rust_crate(
             crate = name,
             env = test_env,
             deps = all_crate_deps(normal = True, normal_dev = True) + maybe_deps + deps_extra,
-            rustc_flags = rustc_flags_extra,
+            # Keep `file!()` paths Cargo-like (`core/src/...`) instead of
+            # Bazel workspace-prefixed (`codex-rs/core/src/...`) for snapshot parity.
+            rustc_flags = rustc_flags_extra + ["--remap-path-prefix=codex-rs="],
             rustc_env = rustc_env,
             data = test_data_extra,
             tags = test_tags,
@@ -178,7 +180,7 @@ def codex_rust_crate(
             rustc_flags = rustc_flags_extra + ["--remap-path-prefix=codex-rs="],
             rustc_env = rustc_env,
             # Important: do not merge `test_env` here. Its unit-test-only
-            # `INSTA_WORKSPACE_ROOT="."` can point integration tests at the
+            # `INSTA_WORKSPACE_ROOT="codex-rs"` can point integration tests at the
             # runfiles cwd and cause false `.snap.new` churn on Linux.
             env = cargo_env,
             tags = test_tags,