diff --git a/src/libstore/tests/downstream-placeholder.cc b/src/libstore/tests/downstream-placeholder.cc
new file mode 100644
index 000000000..7b8e2c649
--- /dev/null
+++ b/src/libstore/tests/downstream-placeholder.cc
@@ -0,0 +1,16 @@
+#include <gtest/gtest.h>
+
+#include "derivations.hh"
+
+namespace nix {
+
+TEST(Derivation, downstreamPlaceholder) {
+    ASSERT_EQ(
+        downstreamPlaceholder(
+            (const Store &)*(const Store *)nullptr, // argument is unused
+            StorePath { "g1w7hy3qg1w7hy3qg1w7hy3qg1w7hy3q-foo.drv" },
+            "out"),
+        "/0c6rn30q4frawknapgwq386zq358m8r6msvywcvc89n6m5p2dgbz");
+}
+
+}