diff --git a/opm/simulators/linalg/cuistl/detail/vector_operations.cu b/opm/simulators/linalg/cuistl/detail/vector_operations.cu
index 5c7223870..c557c9b7a 100644
--- a/opm/simulators/linalg/cuistl/detail/vector_operations.cu
+++ b/opm/simulators/linalg/cuistl/detail/vector_operations.cu
@@ -54,7 +54,7 @@ namespace
         // TODO: [perf] Is it faster to just use a mask? Probably does not matter either way
         //              This is hopefully not where we will spend most of our time.
         if (globalIndex < numberOfElements) {
-            buffer[indices[globalIndex]] = a[indices[globalIndex]] * b[indices[globalIndex]];
+            buffer[globalIndex] = a[indices[globalIndex]] * b[indices[globalIndex]];
         }
     }
 
diff --git a/tests/cuistl/test_cuvector.cpp b/tests/cuistl/test_cuvector.cpp
index be516de2b..dc41cc47e 100644
--- a/tests/cuistl/test_cuvector.cpp
+++ b/tests/cuistl/test_cuvector.cpp
@@ -280,5 +280,16 @@ BOOST_AUTO_TEST_CASE(RandomVectors)
                 BOOST_CHECK_EQUAL(projectedA[i], a[i]);
             }
         }
+
+        aGPU = GVector(a);
+        auto twoNormAtIndices = aGPU.two_norm(indexSetGPU);
+
+        double correctTwoNormAtIndices = 0.0;
+        for (size_t i = 0; i < indexSet.size(); ++i) {
+            correctTwoNormAtIndices += a[indexSet[i]] * a[indexSet[i]];
+        }
+        correctTwoNormAtIndices = std::sqrt(correctTwoNormAtIndices);
+
+        BOOST_CHECK_CLOSE(correctTwoNormAtIndices, twoNormAtIndices, 1e-7);
     }
 }