diff --git a/tdishr/TdiExtFunction.c b/tdishr/TdiExtFunction.c
index cdc195e07b..1dbe977df4 100644
--- a/tdishr/TdiExtFunction.c
+++ b/tdishr/TdiExtFunction.c
@@ -85,13 +85,17 @@ static void tmp_cleanup(void *tmp_in)
   for (; --tmp->n >= 0;)
     MdsFree1Dx(&tmp->a[tmp->n], NULL);
 }
+
+// TDI's EXT_FUNCTION is used to execute *.fun files, but doesn't execute functions in external libraries.
 int Tdi1ExtFunction(opcode_t opcode __attribute__((unused)), int narg,
                     struct descriptor *list[], struct descriptor_xd *out_ptr)
 {
   int status;
   struct descriptor_d image = EMPTY_D, entry = EMPTY_D;
+  struct descriptor_d new_entry = EMPTY_D;
   FREED_ON_EXIT(&image);
   FREED_ON_EXIT(&entry);
+  FREED_ON_EXIT(&new_entry);
   status = MDSplusSUCCESS;
   if (list[0])
     status = TdiData(list[0], &image MDS_END_ARG);
@@ -112,7 +116,26 @@ int Tdi1ExtFunction(opcode_t opcode __attribute__((unused)), int narg,
     goto done;
   }
 
-  status = TdiFindImageSymbol(&image, &entry, &routine);
+
+  // (MW) TODOD: Consider deprecating the rest of this routine on all platforms.
+  // The EXT_FUNCTION feature to call a function in a library was broken on Ubuntu x86-64
+  // well before the port to Apple Silicon.  Thus the Apple Silicon code added here also segfaults.
+  // Note that BUILD_CALL (aka ->) is used for most calls to external libraries.
+  // ALso, MAKE_CALL creates / executes an EXT_FUNCTION (presumably just for *.fun files).
+  if (STATUS_OK) {
+    char *c_entry = MdsDescrToCstring(&entry);
+    char *hash_ptr =strrchr(c_entry, '#');
+    if (hash_ptr == NULL) {
+      status = TdiFindImageSymbol(&image, &entry, &routine);
+    } else {
+      char *dup_entry = strdup(strtok(c_entry, "#"));
+      new_entry.length = strlen(dup_entry);
+      new_entry.pointer = dup_entry;
+      status = TdiFindImageSymbol(&image, &new_entry, &routine);
+      free(dup_entry);
+    }
+    free(c_entry);
+  }
   /**********************************************
   Requires: image found and routine symbol found.
   **********************************************/
@@ -181,9 +204,51 @@ int Tdi1ExtFunction(opcode_t opcode __attribute__((unused)), int narg,
        *************************/
     if (STATUS_OK)
     {
-      struct descriptor_s out = {sizeof(void *), DTYPE_POINTER, CLASS_S,
-                                 LibCallg(&new[0], routine)};
-      MdsCopyDxXd((struct descriptor *)&out, out_ptr);
+
+#ifdef MDSPLUS_USE_FFI
+      char *c_entry = MdsDescrToCstring(&entry);
+      char *hash_ptr = strrchr(c_entry, '#');
+      int bypass_ffi = TRUE;
+      int num_fixed_args = 0;
+      if (hash_ptr != NULL) {
+        hash_ptr++;
+        num_fixed_args = atoi(hash_ptr);
+      }
+      if (num_fixed_args != 0) {
+        bypass_ffi = FALSE;
+      }
+      free(c_entry);      
+#else
+      int bypass_ffi = TRUE;  // for Linux, Windows, and MacOS(Intel)
+      int num_fixed_args = 0;
+#endif
+
+      if (bypass_ffi) {
+        struct descriptor_s out = {sizeof(void *), DTYPE_POINTER, CLASS_S, LibCallg(&new[0], (routine))}; 
+        MdsCopyDxXd((struct descriptor *)&out, out_ptr);
+
+      // Depending on the external function being called, additional "case" clauses might be required.
+      // Use of TRUE is because case must start with a statement.
+      // Struct declaration can't be declared here because it would evaluate the LibCallg*() prematurely.
+      // (MW) TODO: If it is decided to implement this WIP, then this code needs to be refactored for clarity,
+      // and edge cases need to be handled.
+      } else {
+        switch(num_fixed_args) {
+  #ifdef MDSPLUS_USE_FFI  
+        case 1:
+          TRUE;
+          // Is MDS_FFI_RTN_POINTER correct here?   Chose that because the descriptor is DTYPE_POINTER.
+          struct descriptor_s out1 = {sizeof(void *), DTYPE_POINTER, CLASS_S, LibCallgFfi(&new[0], (routine), 1, MDS_FFI_RTN_POINTER)};
+          MdsCopyDxXd((struct descriptor *)&out1, out_ptr);
+          break;
+  #endif
+        default:
+          TRUE;
+          struct descriptor_s out = {sizeof(void *), DTYPE_POINTER, CLASS_S, LibCallg(&new[0], (routine))}; 
+          MdsCopyDxXd((struct descriptor *)&out, out_ptr);
+          break;
+        }
+      }
     }
     pthread_cleanup_pop(1);
   }
@@ -192,5 +257,6 @@ int Tdi1ExtFunction(opcode_t opcode __attribute__((unused)), int narg,
 done:;
   FREED_NOW(&entry);
   FREED_NOW(&image);
+  FREED_NOW(&new_entry);
   return status;
 }