diff --git a/bin/genEvalSpecializations.py b/bin/genEvalSpecializations.py
index 1f3cb770e..87f71ea33 100755
--- a/bin/genEvalSpecializations.py
+++ b/bin/genEvalSpecializations.py
@@ -79,7 +79,7 @@ specializationTemplate = \
 #include <opm/material/common/Valgrind.hpp>
 
 {% if numDerivs < 0 %}\
-#include <vector>
+#include "FastSmallVector.hpp"
 {% else %}\
 #include <array>
 {% endif %}\
@@ -180,8 +180,13 @@ protected:
     void checkDefined_() const
     {
 #ifndef NDEBUG
+{% if numDerivs < 0 %}\
+        for (int i = dstart_(); i < dend_(); ++i)
+            Valgrind::CheckDefined(data_[i]);
+{% else %}\
        for (const auto& v: data_)
            Valgrind::CheckDefined(v);
+{% endif %}\
 #endif
     }
 
@@ -728,7 +733,7 @@ public:
 private:
 
 {% if numDerivs < 0 %}\
-    std::vector<ValueT> data_;
+    FastSmallVector<ValueT, 9> data_;
 {% elif numDerivs == 0 %}\
     std::array<ValueT, numDerivs + 1> data_;
 {% else %}\
diff --git a/opm/material/densead/DynamicEvaluation.hpp b/opm/material/densead/DynamicEvaluation.hpp
index 13e5c4fc5..ce8effdef 100644
--- a/opm/material/densead/DynamicEvaluation.hpp
+++ b/opm/material/densead/DynamicEvaluation.hpp
@@ -34,11 +34,10 @@
 
 #include "Evaluation.hpp"
 #include "Math.hpp"
-#include "FastSmallVector.hpp"
 
 #include <opm/material/common/Valgrind.hpp>
 
-#include <vector>
+#include "FastSmallVector.hpp"
 #include <cmath>
 #include <cassert>
 #include <cstring>
@@ -519,7 +518,7 @@ public:
 
 private:
 
-    FastSmallVector<ValueT, 8> data_;
+    FastSmallVector<ValueT, 9> data_;
 };
 
 template <class Scalar>