diff --git a/src/min.cpp b/src/min.cpp
index 6322b96f77..eebfd03dcd 100644
--- a/src/min.cpp
+++ b/src/min.cpp
@@ -533,11 +533,13 @@ void Min::force_clear()
 
   size_t nbytes = sizeof(double) * nall;
 
-  memset(&(atom->f[0][0]),0,3*nbytes);
-  if (torqueflag)  memset(&(atom->torque[0][0]),0,3*nbytes);
-  if (erforceflag) memset(&(atom->erforce[0]),  0,  nbytes);
-  if (e_flag)      memset(&(atom->de[0]),       0,  nbytes);
-  if (rho_flag)    memset(&(atom->drho[0]),     0,  nbytes);
+  if (nbytes) {
+    memset(&(atom->f[0][0]),0,3*nbytes);
+    if (torqueflag)  memset(&(atom->torque[0][0]),0,3*nbytes);
+    if (erforceflag) memset(&(atom->erforce[0]),  0,  nbytes);
+    if (e_flag)      memset(&(atom->de[0]),       0,  nbytes);
+    if (rho_flag)    memset(&(atom->drho[0]),     0,  nbytes);
+  }
 }
 
 /* ----------------------------------------------------------------------