diff --git a/src/GRANULAR/gran_sub_mod_damping.cpp b/src/GRANULAR/gran_sub_mod_damping.cpp
index 7d6a02b8f0..c635d90265 100644
--- a/src/GRANULAR/gran_sub_mod_damping.cpp
+++ b/src/GRANULAR/gran_sub_mod_damping.cpp
@@ -130,6 +130,8 @@ void GranSubModDampingTsuji::init()
 
 double GranSubModDampingTsuji::calculate_forces()
 {
-  damp_prefactor = damp * sqrt(gm->meff * gm->Fnormal / gm->delta);
+  // in case argument < 0 due to precision issues
+  double sqrt1 = MAX(0, gm->meff * gm->Fnormal / gm->delta);
+  damp_prefactor = damp * sqrt(sqrt1);
   return -damp_prefactor * gm->vnnr;
 }