diff --git a/bin/CMakeLists.txt b/bin/CMakeLists.txt
index 5b156d2..3ef4f79 100644
--- a/bin/CMakeLists.txt
+++ b/bin/CMakeLists.txt
@@ -10,12 +10,12 @@ ExternalProject_Add(
 	INSTALL_COMMAND ""
 	PREFIX "external"
 	)
-ExternalProject_Get_Property(json_hpp install_dir)
+ExternalProject_Get_Property(json_hpp download_dir)
 
 foreach(entry ${CATIMA_APPS})
     add_executable(${entry} ${entry}.cpp)
     target_link_libraries(${entry} catima)
-    target_include_directories(${entry} PRIVATE ${install_dir})
+    target_include_directories(${entry} PRIVATE ${download_dir})
 endforeach(entry in ${CATIMA_APPS})
 
 install (TARGETS ${CATIMA_APPS} RUNTIME DESTINATION bin)
diff --git a/catima.cpp b/catima.cpp
index 931f66c..7ebe337 100644
--- a/catima.cpp
+++ b/catima.cpp
@@ -149,7 +149,6 @@ double energy_straggling_from_E(Projectile &p, double T, double Tout,const Mater
 }
 
 double energy_out(double T, double thickness, const Interpolator &range_spline){
-    constexpr double epsilon = 1E-5;
     int counter = 0;
     double range;
     double dedx;
@@ -162,13 +161,14 @@ double energy_out(double T, double thickness, const Interpolator &range_spline){
     e = T - (thickness*dedx);
     while(1){
         r = range - range_spline(e) - thickness;
-        if(fabs(r)<epsilon)return e;
+        if(fabs(r)<Eout_epsilon)return e;
         double step = -r*dedx;
         e = e-step;
         if(e<Ezero)return 0.0;
         dedx = 1.0/range_spline.derivative(e);
         counter++;
-        if(counter>100){printf("too many iterations finding Eout");return -1;}
+        assert(counter<=100);
+        if(counter>100)return -1;
     }
     return -1;
 }
diff --git a/constants.h b/constants.h
index 6032f92..6125471 100644
--- a/constants.h
+++ b/constants.h
@@ -11,6 +11,7 @@ constexpr double logEmax = 7.0;  // log of max energy
 constexpr int max_datapoints = 500; // how many datapoints between logEmin and logEmax
 constexpr int max_storage_data = 60; // number of datapoints which can be stored in cache
 constexpr double numeric_epsilon = 10*std::numeric_limits<double>::epsilon();
+constexpr double Eout_epsilon = 1e-5;  //
 
 constexpr double thin_target_limit = 1 - 1e-3;
 
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 745bd70..7d89935 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -1,17 +1,19 @@
-add_definitions(-Dlest_FEATURE_COLOURISE=1)
+find_package(doctest REQUIRED)
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/tests)
 
 set(CATIMA_TESTS test_calculations test_generated test_storage test_structures test_dedx_range test_abundances)
 
 foreach(entry ${CATIMA_TESTS})
     add_executable(${entry} ${entry}.cpp)
-    target_link_libraries(${entry} catima)
+    target_link_libraries(${entry} PRIVATE catima)
+    target_compile_features(${entry} PRIVATE cxx_std_17)
     add_test(${entry} ${PROJECT_BINARY_DIR}/tests/${entry})
 endforeach(entry in ${CATIMA_TESTS})
 
 if(REACTIONS)
     add_executable(test_reaction test_reaction.cpp)
     target_link_libraries(test_reaction catima)
+    target_compile_features(test_reaction PRIVATE cxx_std_17)
     add_test(test_reaction ${PROJECT_BINARY_DIR}/tests/test_reaction)
 endif(REACTIONS)
 
@@ -20,4 +22,5 @@ MESSAGE( STATUS "CMAKE_C_COMPILER: " ${CMAKE_C_COMPILER} )
 foreach(entry ${C_TESTS})
     add_executable(${entry} ${entry}.c)
     target_link_libraries(${entry} catima)
+    target_compile_features(${entry} PRIVATE cxx_std_17)
 endforeach(entry in ${C_TESTS})