diff --git a/calculations.cpp b/calculations.cpp
index f4413e0..3d25c1d 100644
--- a/calculations.cpp
+++ b/calculations.cpp
@@ -559,7 +559,7 @@ double angular_scattering_variance(Projectile &p, Target &t){
 }
 
 /// radioation lengths are taken frm Particle Data Group 2014
-double radiation_length(int z, int m){
+double radiation_length(int z, double m){
     double lr = 0;
     if(z==1){return 63.04;}
     if(z==2){return 94.32;}
diff --git a/calculations.h b/calculations.h
index 25be496..a9b0449 100644
--- a/calculations.h
+++ b/calculations.h
@@ -95,10 +95,11 @@ namespace catima{
     /**
       * returns radiation length of the (M,Z) material
       * for certain z the radiation length is tabulated, otherwise calculated
-      * @param z - proton number of material
+      * @param z - proton number of target
+      * @param m - weight of the target
       * @return radiation length in g/cm^2
       */
-    double radiation_length(int z, int m);
+    double radiation_length(int z, double m);
     
     /** returns effective Z of the projectile
       * @param c - Configuration, the z effective will be calculated according to c.z_effective value
diff --git a/tests/test_calculations.cpp b/tests/test_calculations.cpp
index def28bd..824a06d 100644
--- a/tests/test_calculations.cpp
+++ b/tests/test_calculations.cpp
@@ -170,7 +170,7 @@ const lest::test specification[] =
       
       auto res = catima::calculate(p,graphite);
       dif = res.Eout - 997.077;
-      EXPECT( fabs(dif) < 0.01);
+      EXPECT( res.Eout == approx(997.07,01));
     },
   CASE("TOF test"){
       catima::Projectile p{12,6,6,1000};
@@ -295,7 +295,7 @@ const lest::test specification[] =
         EXPECT(res.results[0].range == approx(107.163,0.1));
         EXPECT(res.results[1].Eout == approx(926.3,0.1));
         EXPECT(res.results[1].sigma_a == approx(0.000774).R(0.05));
-        EXPECT(res.results[1].range == approx(110.8,0.1));
+        EXPECT(res.results[1].range == approx(111.3,0.1));
 
         auto res0 = catima::calculate(p(1000),water);
         EXPECT(res0.Eout == res.results[0].Eout);