diff --git a/postgres_ffi/src/xlog_utils.rs b/postgres_ffi/src/xlog_utils.rs
index d2b2b5c122..89fdbbf7ac 100644
--- a/postgres_ffi/src/xlog_utils.rs
+++ b/postgres_ffi/src/xlog_utils.rs
@@ -495,7 +495,13 @@ mod tests {
             .env("DYLD_LIBRARY_PATH", &lib_path)
             .output()
             .unwrap();
-        assert!(initdb_output.status.success());
+        assert!(
+            initdb_output.status.success(),
+            "initdb failed. Status: '{}', stdout: '{}', stderr: '{}'",
+            initdb_output.status,
+            String::from_utf8_lossy(&initdb_output.stdout),
+            String::from_utf8_lossy(&initdb_output.stderr),
+        );
 
         // 2. Pick WAL generated by initdb
         let wal_dir = data_dir.join("pg_wal");