diff --git a/src/modify.cpp b/src/modify.cpp
index 0d4ae4d2cf..03622e5940 100644
--- a/src/modify.cpp
+++ b/src/modify.cpp
@@ -33,7 +33,7 @@ using namespace FixConst;
 
 #define DELTA 4
 #define BIG 1.0e20
-#define NEXCEPT 5       // change when add to exceptions in add_fix()
+#define NEXCEPT 6       // change when add to exceptions in add_fix()
 
 /* ---------------------------------------------------------------------- */
 
@@ -697,7 +697,7 @@ void Modify::add_fix(int narg, char **arg, int trysuffix)
   // MUST change NEXCEPT above when add new fix to this list
 
   const char *exceptions[NEXCEPT] =
-    {"GPU","OMP","INTEL","property/atom","cmap"};
+    {"GPU","OMP","INTEL","property/atom","cmap","rx"};
 
   if (domain->box_exist == 0) {
     int m;