diff --git a/src/KSPACE/ewald.cpp b/src/KSPACE/ewald.cpp
index d0a78dd922..f5fb680f51 100644
--- a/src/KSPACE/ewald.cpp
+++ b/src/KSPACE/ewald.cpp
@@ -157,10 +157,11 @@ void Ewald::init()
   // zprd used rather than zprd_slab
 
   if (!gewaldflag) {
+    if (accuracy <= 0.0)
+      error->all(FLERR,"KSpace accuracy must be > 0");
     g_ewald = accuracy*sqrt(natoms*cutoff*xprd*yprd*zprd) / (2.0*q2);
-    if (g_ewald >= 1.0)
-      error->all(FLERR,"KSpace accuracy too large to estimate G vector");
-    g_ewald = sqrt(-log(g_ewald)) / cutoff;
+    if (g_ewald >= 1.0) g_ewald = (1.35 - 0.15*log(accuracy))/cutoff;
+    else g_ewald = sqrt(-log(g_ewald)) / cutoff;
   }
 
   // setup Ewald coefficients so can print stats
diff --git a/src/KSPACE/ewald.h b/src/KSPACE/ewald.h
index 858c475073..f4cd938cac 100644
--- a/src/KSPACE/ewald.h
+++ b/src/KSPACE/ewald.h
@@ -119,9 +119,9 @@ W: System is not charge neutral, net charge = %g
 The total charge on all atoms on the system is not 0.0, which
 is not valid for Ewald or PPPM.
 
-E: KSpace accuracy too large to estimate G vector
+E: KSpace accuracy must be > 0
 
-UNDOCUMENTED
+The kspace accuracy designated in the input must be greater than zero.
 
 E: Cannot (yet) use Kspace slab correction with compute group/group
 
diff --git a/src/KSPACE/pppm.cpp b/src/KSPACE/pppm.cpp
index 560389b1fa..74479551d4 100644
--- a/src/KSPACE/pppm.cpp
+++ b/src/KSPACE/pppm.cpp
@@ -1003,10 +1003,11 @@ void PPPM::set_grid()
   bigint natoms = atom->natoms;
 
   if (!gewaldflag) {
+    if (accuracy <= 0.0)
+      error->all(FLERR,"KSpace accuracy must be > 0");
     g_ewald = accuracy*sqrt(natoms*cutoff*xprd*yprd*zprd) / (2.0*q2);
-    if (g_ewald >= 1.0)
-      error->all(FLERR,"KSpace accuracy too large to estimate G vector");
-    g_ewald = sqrt(-log(g_ewald)) / cutoff;
+    if (g_ewald >= 1.0) g_ewald = (1.35 - 0.15*log(accuracy))/cutoff;
+    else g_ewald = sqrt(-log(g_ewald)) / cutoff;
   }
 
   // set optimal nx_pppm,ny_pppm,nz_pppm based on order and accuracy
diff --git a/src/KSPACE/pppm.h b/src/KSPACE/pppm.h
index 25407fb7fb..849b08322f 100644
--- a/src/KSPACE/pppm.h
+++ b/src/KSPACE/pppm.h
@@ -245,9 +245,9 @@ to run, but can reduce the order no further.  Try increasing the
 accuracy of PPPM by reducing the tolerance size, thus inducing a
 larger PPPM grid.
 
-E: KSpace accuracy too large to estimate G vector
+E: KSpace accuracy must be > 0
 
-UNDOCUMENTED
+The kspace accuracy designated in the input must be greater than zero.
 
 E: Cannot compute PPPM G