Index: branches/czw_branch/20170908/Ohana/src/opihi/lib.shell/evaluate_stack.c
===================================================================
--- branches/czw_branch/20170908/Ohana/src/opihi/lib.shell/evaluate_stack.c	(revision 40206)
+++ branches/czw_branch/20170908/Ohana/src/opihi/lib.shell/evaluate_stack.c	(revision 40207)
@@ -188,5 +188,12 @@
 	  snprintf (line, 512, "syntax error: invalid operand for binary operation: %s or %s\n", stack[i-1].name, stack[i-2].name);
 	  push_error (line);
-	  if (strchr(stack[i-1].name, ':') || strchr(stack[i-2].name, ':')) {
+	  int isTrinary = TRUE;
+	  isTrinary = isTrinary && (i >= 2);
+	  // isTrinary = isTrinary && (stack[i - 1] != NULL);
+	  // isTrinary = isTrinary && (stack[i - 2] != NULL);
+	  isTrinary = isTrinary && (stack[i - 1].name != NULL);
+	  isTrinary = isTrinary && (stack[i - 2].name != NULL);
+	  isTrinary = isTrinary && (strchr(stack[i-1].name, ':') || strchr(stack[i-2].name, ':'));
+	  if (isTrinary) {
 	    snprintf (line, 512, "syntax error: invalid operand for binary operation: %s or %s\n(Note that the : in a trinary operation must be protected by spaces)\n", stack[i-1].name, stack[i-2].name);
 	    push_error (line);