diff --git a/tutorial/ex3/fluidsystems/h2omycompressiblecomponent.hh b/tutorial/ex3/fluidsystems/h2omycompressiblecomponent.hh
index b02bce33982c161b01176f0ab74cf283891eb952..f92d729a3c2026a0f2a6ac098235fe2ed6bbef50 100644
--- a/tutorial/ex3/fluidsystems/h2omycompressiblecomponent.hh
+++ b/tutorial/ex3/fluidsystems/h2omycompressiblecomponent.hh
@@ -279,7 +279,8 @@ public:
                                              int compJIdx)
     {
         assert(0 <= phaseIdx  && phaseIdx < numPhases);
-        assert(0 <= compIdx  && compIdx < numComponents);
+        assert(0 <= compIIdx  && compIIdx < numComponents);
+        assert(0 <= compJIdx  && compJIdx < numComponents);
 
         const Scalar T = fluidState.temperature(phaseIdx);
         const Scalar p = fluidState.pressure(phaseIdx);