--- include/vigra/mathutil.hxx.orig	2018-10-19 16:12:20 UTC
+++ include/vigra/mathutil.hxx
@@ -675,7 +675,12 @@ VIGRA_DEFINE_NORM(int)
 VIGRA_DEFINE_NORM(unsigned int)
 VIGRA_DEFINE_NORM(long)
 VIGRA_DEFINE_NORM(unsigned long)
+#if defined(__FreeBSD__) || defined(__DragonFly__)
+inline NormTraits<long long>::SquaredNormType squaredNorm(long long t) { return sq((long int) t); }
+inline NormTraits<long long>::NormType norm(long long t) { return abs((long int) t); }
+#else
 VIGRA_DEFINE_NORM(long long)
+#endif
 VIGRA_DEFINE_NORM(unsigned long long)
 VIGRA_DEFINE_NORM(float)
 VIGRA_DEFINE_NORM(double)