diff --git a/src/lmptype.h b/src/lmptype.h
index bf56d07d77..a5aa08e390 100644
--- a/src/lmptype.h
+++ b/src/lmptype.h
@@ -95,6 +95,8 @@ typedef int64_t bigint;
 #define MAXSMALLINT INT_MAX
 #define MAXTAGINT INT_MAX
 #define MAXBIGINT INT64_MAX
+// INT64_MAX cannot be represented with a double. reduce to avoid overflow when casting back.
+#define MAXBIGINT_DOUBLE (INT64_MAX-512)
 
 #define MPI_LMP_TAGINT MPI_INT
 #define MPI_LMP_IMAGEINT MPI_INT
@@ -132,6 +134,8 @@ typedef int64_t bigint;
 #define MAXSMALLINT INT_MAX
 #define MAXTAGINT INT64_MAX
 #define MAXBIGINT INT64_MAX
+// INT64_MAX cannot be represented with a double. reduce to avoid overflow when casting back.
+#define MAXBIGINT_DOUBLE (INT64_MAX-512)
 
 #define MPI_LMP_TAGINT MPI_LL
 #define MPI_LMP_IMAGEINT MPI_LL
@@ -168,6 +172,7 @@ typedef int bigint;
 #define MAXSMALLINT INT_MAX
 #define MAXTAGINT INT_MAX
 #define MAXBIGINT INT_MAX
+#define MAXBIGINT_DOUBLE INT_MAX
 
 #define MPI_LMP_TAGINT MPI_INT
 #define MPI_LMP_IMAGEINT MPI_INT
diff --git a/src/variable.cpp b/src/variable.cpp
index 2d6d4694d1..d26c0185db 100644
--- a/src/variable.cpp
+++ b/src/variable.cpp
@@ -2721,8 +2721,8 @@ double Variable::collapse_tree(Tree *tree)
     else if (update->ntimestep < ivalue2) {
       bigint offset = update->ntimestep - ivalue1;
       tree->value = ivalue1 + (offset/ivalue3)*ivalue3 + ivalue3;
-      if (tree->value > ivalue2) tree->value = (double) MAXBIGINT;
-    } else tree->value = (double) MAXBIGINT;
+      if (tree->value > ivalue2) tree->value = (double) MAXBIGINT_DOUBLE;
+    } else tree->value = (double) MAXBIGINT_DOUBLE;
     return tree->value;
   }
 
@@ -2758,11 +2758,11 @@ double Variable::collapse_tree(Tree *tree)
         if (istep > ivalue5) {
           offset = ivalue5 - ivalue1;
           istep = ivalue1 + (offset/ivalue3)*ivalue3 + ivalue3;
-          if (istep > ivalue2) istep = MAXBIGINT;
+          if (istep > ivalue2) istep = MAXBIGINT_DOUBLE;
         }
       }
-    } else istep = MAXBIGINT;
-    tree->value = istep;
+    } else istep = MAXBIGINT_DOUBLE;
+    tree->value = (double)istep;
     return tree->value;
   }
 
@@ -3060,8 +3060,8 @@ double Variable::eval_tree(Tree *tree, int i)
     else if (update->ntimestep < ivalue2) {
       bigint offset = update->ntimestep - ivalue1;
       arg = ivalue1 + (offset/ivalue3)*ivalue3 + ivalue3;
-      if (arg > ivalue2) arg = (double) MAXBIGINT;
-    } else arg = (double) MAXBIGINT;
+      if (arg > ivalue2) arg = (double) MAXBIGINT_DOUBLE;
+    } else arg = (double) MAXBIGINT_DOUBLE;
     return arg;
   }
 
@@ -3092,10 +3092,10 @@ double Variable::eval_tree(Tree *tree, int i)
         if (istep > ivalue5) {
           offset = ivalue5 - ivalue1;
           istep = ivalue1 + (offset/ivalue3)*ivalue3 + ivalue3;
-          if (istep > ivalue2) istep = MAXBIGINT;
+          if (istep > ivalue2) istep = MAXBIGINT_DOUBLE;
         }
       }
-    } else istep = MAXBIGINT;
+    } else istep = MAXBIGINT_DOUBLE;
     arg = istep;
     return arg;
   }
@@ -3627,8 +3627,8 @@ int Variable::math_function(char *word, char *contents, Tree **tree, Tree **tree
       else if (update->ntimestep < ivalue2) {
         bigint offset = update->ntimestep - ivalue1;
         value = ivalue1 + (offset/ivalue3)*ivalue3 + ivalue3;
-        if (value > ivalue2) value = (double) MAXBIGINT;
-      } else value = (double) MAXBIGINT;
+        if (value > ivalue2) value = (double) MAXBIGINT_DOUBLE;
+      } else value = (double) MAXBIGINT_DOUBLE;
       argstack[nargstack++] = value;
     }
 
@@ -3662,10 +3662,10 @@ int Variable::math_function(char *word, char *contents, Tree **tree, Tree **tree
           if (istep > ivalue5) {
             offset = ivalue5 - ivalue1;
             istep = ivalue1 + (offset/ivalue3)*ivalue3 + ivalue3;
-            if (istep > ivalue2) istep = MAXBIGINT;
+            if (istep > ivalue2) istep = MAXBIGINT_DOUBLE;
           }
         }
-      } else istep = MAXBIGINT;
+      } else istep = MAXBIGINT_DOUBLE;
       double value = istep;
       argstack[nargstack++] = value;
     }