diff --git a/rust/ql/test/library-tests/dataflow/sources/InlineFlow.ql b/rust/ql/test/library-tests/dataflow/sources/InlineFlow.ql
index 92a41dc4681..7d5f4fb926f 100644
--- a/rust/ql/test/library-tests/dataflow/sources/InlineFlow.ql
+++ b/rust/ql/test/library-tests/dataflow/sources/InlineFlow.ql
@@ -14,6 +14,12 @@ module MyFlowConfig implements DataFlow::ConfigSig {
         .getArgList()
         .getAnArg() = sink.asExpr().getExpr()
   }
+
+  predicate allowImplicitRead(DataFlow::Node node, DataFlow::ContentSet c) {
+    // flow out from any content at the sink.
+    isSink(node) and
+    exists(c)
+  }
 }
 
 module MyFlowTest = TaintFlowTest<MyFlowConfig>;
diff --git a/rust/ql/test/library-tests/dataflow/sources/test.rs b/rust/ql/test/library-tests/dataflow/sources/test.rs
index 9b92bb41b21..449828cb995 100644
--- a/rust/ql/test/library-tests/dataflow/sources/test.rs
+++ b/rust/ql/test/library-tests/dataflow/sources/test.rs
@@ -5,8 +5,8 @@ fn sink<T>(_: T) { }
 // --- tests ---
 
 fn test_env_vars() {
-    sink(std::env::var("HOME")); // $ Alert[rust/summary/taint-sources] MISSING: hasTaintFlow
-    sink(std::env::var_os("PATH")); // $ Alert[rust/summary/taint-sources] MISSING: hasTaintFlow
+    sink(std::env::var("HOME")); // $ Alert[rust/summary/taint-sources] hasTaintFlow="HOME"
+    sink(std::env::var_os("PATH")); // $ Alert[rust/summary/taint-sources] hasTaintFlow="PATH"
 
     let var1 = std::env::var("HOME").expect("HOME not set"); // $ Alert[rust/summary/taint-sources]
     let var2 = std::env::var_os("PATH").unwrap(); // $ Alert[rust/summary/taint-sources]