diff --git a/include/crpropa/magneticField/turbulentField/TurbulentField.h b/include/crpropa/magneticField/turbulentField/TurbulentField.h
index c7f79aeee0..8b478d89fc 100644
--- a/include/crpropa/magneticField/turbulentField/TurbulentField.h
+++ b/include/crpropa/magneticField/turbulentField/TurbulentField.h
@@ -49,7 +49,7 @@ class TurbulenceSpectrum : public Referenced {
 	 range
 	*/
 	TurbulenceSpectrum(double Brms, double lMin, double lMax,
-	                   double lBendover = 1, double sIndex = 5. / 3.,
+	                   double lBendover = 1, double sIndex = (5. / 3.),
 	                   double qIndex = 4)
 	    : Brms(Brms), lMin(lMin), lMax(lMax), lBendover(lBendover),
 	      sIndex(sIndex), qIndex(qIndex) {
diff --git a/test/testPythonExtension.py b/test/testPythonExtension.py
index 818f41151e..49738ca5a7 100644
--- a/test/testPythonExtension.py
+++ b/test/testPythonExtension.py
@@ -204,6 +204,16 @@ def testGridPropertiesConstructor(self):
 
 if hasattr(crp, 'GridTurbulence'):
     class testTurbulentField(unittest.TestCase):
+      #check problems brought up in https://github.com/CRPropa/CRPropa3/issues/322
+      def testTurbulenceSpectrum(self):
+        spectrum = crp.TurbulenceSpectrum(1., 1., 10.)
+        self.assertEqual(spectrum.getBrms(), 1.)
+        self.assertEqual(spectrum.getLmin(), 1.)
+        self.assertEqual(spectrum.getLmax(), 10.)
+        self.assertEqual(spectrum.getLbendover(), 1.)
+        self.assertEqual(spectrum.getSindex(), 5./3.)
+        self.assertEqual(spectrum.getQindex(), 4.)
+
       def testGridTurbulence(self):
         N = 64
         boxSize = 1*crp.Mpc
diff --git a/test/testTurbulentField.cpp b/test/testTurbulentField.cpp
index 18d45e644f..2b04244d2d 100644
--- a/test/testTurbulentField.cpp
+++ b/test/testTurbulentField.cpp
@@ -13,6 +13,23 @@
 
 using namespace crpropa;
 
+//check problems brought up in https://github.com/CRPropa/CRPropa3/issues/322
+TEST(testTurbulenceSpectrum, constructor) {
+	double sIndex = 5./3.;
+	double qIndex = 4.;
+	double bendOver = 1.;
+	double lMin = 1.; 
+	double lMax = 10.; 
+	double brms = 1*muG;
+	auto spectrum = TurbulenceSpectrum(brms, lMin, lMax);
+	EXPECT_DOUBLE_EQ(spectrum.getBrms(), brms);
+	EXPECT_DOUBLE_EQ(spectrum.getLmin(), lMin);
+	EXPECT_DOUBLE_EQ(spectrum.getLmax(), lMax);
+	EXPECT_DOUBLE_EQ(spectrum.getLbendover(), bendOver); //default
+	EXPECT_DOUBLE_EQ(spectrum.getSindex(), sIndex); //default
+	EXPECT_DOUBLE_EQ(spectrum.getQindex(), qIndex); //default
+}
+
 TEST(testTurbulenceSpectrum, correlationLength) {
 	double lMin = 0.00001; // not used for Lc
 	double lMax = 9999999; // not used for Lc