diff --git a/src/meson.build b/src/meson.build
index f5bd27ae..d85be960 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -80,6 +80,7 @@ test(
     'rstest',
     cargo_script,
     args: ['test'] + cargo_build_flags,
+    env: ['SOURCE_DIR=' + meson.source_root()],
     # this is a whole Carg-based test suite, let it run for a while
     timeout: 900,
     depends: [build_rstests, cargo_toml],