diff --git a/Engine/csound_orc_compile.c b/Engine/csound_orc_compile.c
index fd684cb92f3..88be5ae788b 100644
--- a/Engine/csound_orc_compile.c
+++ b/Engine/csound_orc_compile.c
@@ -1836,14 +1836,15 @@ int csoundCompileTreeInternal(CSOUND *csound, TREE *root, int async) {
     return CSOUND_ERROR;
   }
 
-  /* now add the instruments with names, assigning them fake instr numbers */
-  named_instr_assign_numbers(csound, engineState);
+
   if (engineState != &csound->engineState) {
     OPDS *ids = csound->ids;
     /* any compilation other than the first one */
     /* merge ENGINE_STATE */
     /* lock to ensure thread-safety */
     if (!async) {
+      /* now add the instruments with names, assigning them fake instr numbers */
+      named_instr_assign_numbers(csound, engineState);
       if (!csound->oparms->realtime)
         csoundLockMutex(csound->API_lock);
       merge_state(csound, engineState, typeTable, ids);
@@ -1857,6 +1858,8 @@ int csoundCompileTreeInternal(CSOUND *csound, TREE *root, int async) {
         csoundSpinUnLock(&csound->alloc_spinlock);
     }
   } else {
+    /* now add the instruments with names, assigning them fake instr numbers */
+    named_instr_assign_numbers(csound, engineState);
     /* first compilation */
     insert_opcodes(csound, csound->opcodeInfo, engineState);
     ip = engineState->instxtanchor.nxtinstxt;
diff --git a/Top/threadsafe.c b/Top/threadsafe.c
index 07ce36c3f0e..8cf7335ea88 100644
--- a/Top/threadsafe.c
+++ b/Top/threadsafe.c
@@ -50,6 +50,8 @@ int csoundScoreEventAbsoluteInternal(CSOUND *csound, char type,
 void set_channel_data_ptr(CSOUND *csound, const char *name,
                           void *ptr, int newSize);
 
+void named_instr_assign_numbers(CSOUND *csound, ENGINE_STATE *engineState);
+
 enum {INPUT_MESSAGE=1, READ_SCORE, SCORE_EVENT, SCORE_EVENT_ABS,
       TABLE_COPY_OUT, TABLE_COPY_IN, TABLE_SET, MERGE_STATE, KILL_INSTANCE};
 
@@ -222,6 +224,7 @@ void message_dequeue(CSOUND *csound) {
                  sizeof(TYPE_TABLE *));
           memcpy(&ids, msg->args + 2*ARG_ALIGN,
                  sizeof(OPDS *));
+          named_instr_assign_numbers(csound, e);
           merge_state(csound, e, t, ids);
         }
         break;