diff --git a/src/enums.hh b/src/enums.hh
index d182db67c7c5e6433fa61dbe741192747b31fdd4..ffe4b77ffd5e35a733802324e6963b219e01328c 100644
--- a/src/enums.hh
+++ b/src/enums.hh
@@ -1,3 +1,6 @@
+#ifndef ENUMS_HH
+#define ENUMS_HH
+
 struct Config {
   enum model {
     Laursen,
@@ -8,3 +11,4 @@ struct Config {
     Ruina
   };
 };
+#endif
diff --git a/src/test-gradient-method-helper.hh b/src/test-gradient-method-helper.hh
index 45e7708b0d53242b74ae5fe3444e0dd03283c282..757336e597cf964ad8bdcb9c77e957cdd7b5787f 100644
--- a/src/test-gradient-method-helper.hh
+++ b/src/test-gradient-method-helper.hh
@@ -1,3 +1,6 @@
+#ifndef TEST_GRADIENT_METHOD_HELPER_HH
+#define TEST_GRADIENT_METHOD_HELPER_HH
+
 #include <boost/format.hpp>
 
 #include <dune/tnnmg/problem-classes/bisection.hh>
@@ -21,3 +24,4 @@ double functionTester(Dune::SampleFunctional<dim> J,
   std::cout << boost::format("%8g -> %e") % original % final << std::endl;
   return final;
 }
+#endif
diff --git a/src/test-gradient-method-nicefunction.hh b/src/test-gradient-method-nicefunction.hh
index 93085e398e7717fba9592945ce1d417708dab72a..eb62eff382e534b1568705c55bec8332f76b414e 100644
--- a/src/test-gradient-method-nicefunction.hh
+++ b/src/test-gradient-method-nicefunction.hh
@@ -1,3 +1,8 @@
+#ifndef TEST_GRADIENT_METHOD_NICEFUNCTION_HH
+#define TEST_GRADIENT_METHOD_NICEFUNCTION_HH
+
+#include <cassert>
+
 #include <dune/tectonic/nicefunction.hh>
 
 namespace Dune {
@@ -113,3 +118,4 @@ class HorribleFunctionLogarithmic : public MyFunction {
   }
 };
 }
+#endif