diff --git a/c32ncp.c b/c32ncp.c
index 128e3ea..eb3d172 100644
--- a/c32ncp.c
+++ b/c32ncp.c
@@ -217,3 +217,93 @@ int c32_ncp87_obtain_rim_attributes(const char *name,
 
   return(0);
 }
+
+
+int c32_ncp87_modify_dos_attributes(char *name,
+                                    uint16 dir_handle,
+                                    uint32 attrs,
+                                    uint16 *actual_out,
+                                    uint16 *handle_lo_out,
+                                    uint16 *handle_hi_out)
+{
+  uint16 handle_lo, handle_hi;
+  uint8 modbuf[64];
+  uint8 path[0x140];
+  uint8 rep0[0x20];
+  uint8 rep1[0x20];
+  uint8 rawout[32];
+  uint8 *p;
+  UI mod_len;
+  UI path_len;
+  uint16 raw_ret_ax, raw_ret_dx;
+  uint16 actual_lo;
+  int rc;
+
+  if (!name)
+    return(1);
+
+  if (actual_out)
+    *actual_out = 0;
+  if (handle_lo_out)
+    *handle_lo_out = 0;
+  if (handle_hi_out)
+    *handle_hi_out = 0;
+
+  rc = c32_get_ncp_handle(&handle_lo, &handle_hi);
+  if (rc)
+    return(10 + rc);
+
+  /*
+   * NCP 87 subfunction 7: Modify DOS information.
+   *
+   * First request fragment contains the fixed header and DOS info structure.
+   * Second request fragment contains the verified SDK-style path structure.
+   *
+   * This avoids the old INT 21h F257 modify path, which can hang under DOS
+   * Client32 for high FLAG bits such as Transactional.
+   */
+  memset(modbuf, 0, sizeof(modbuf));
+  p = modbuf;
+
+  *p++ = 7;                  /* subfunction: modify DOS info */
+  *p++ = 0;                  /* namespace DOS */
+  *p++ = 0;                  /* reserved */
+  c32_put_word_lh(p, 0x0006); p += 2;       /* SA_ALL */
+  c32_put_dword_lh(p, 0x00000004UL); p += 4; /* modify mask: attributes */
+
+  c32_put_dword_lh(p, attrs); p += 4;       /* Attributes */
+  memset(p, 0, 34); p += 34;                /* rest of DOS info */
+  mod_len = (UI)(p - modbuf);
+
+  path_len = c32_build_handle_path(path, (uint8)dir_handle, 0, 0, 1,
+                                  name, NULL, NULL);
+
+  memset(rep0, 0, sizeof(rep0));
+  memset(rep1, 0, sizeof(rep1));
+  memset(rawout, 0, sizeof(rawout));
+
+  C32_NCP87_Raw5_Probe(handle_lo, handle_hi,
+                       modbuf, mod_len,
+                       path, path_len,
+                       rep0, sizeof(rep0),
+                       rep1, sizeof(rep1),
+                       rawout);
+
+  raw_ret_ax = c32_get_word_lh(rawout + 14);
+  raw_ret_dx = c32_get_word_lh(rawout + 16);
+  actual_lo  = c32_get_word_lh(rawout + 18);
+
+  if (actual_out)
+    *actual_out = actual_lo;
+  if (handle_lo_out)
+    *handle_lo_out = handle_lo;
+  if (handle_hi_out)
+    *handle_hi_out = handle_hi;
+
+  if (raw_ret_ax != 0 || raw_ret_dx != 0)
+    return(20);
+
+  return(0);
+}
+
+
diff --git a/c32ncp.h b/c32ncp.h
index aed90bb..471a655 100644
--- a/c32ncp.h
+++ b/c32ncp.h
@@ -11,4 +11,12 @@ int c32_ncp87_obtain_rim_attributes(const char *name,
                                      uint16 *handle_lo_out,
                                      uint16 *handle_hi_out);
 
+
+int c32_ncp87_modify_dos_attributes(char *name,
+                                    uint16 dir_handle,
+                                    uint32 attrs,
+                                    uint16 *actual_out,
+                                    uint16 *handle_lo_out,
+                                    uint16 *handle_hi_out);
+
 #endif
diff --git a/flag.c b/flag.c
index 4c90242..533a792 100644
--- a/flag.c
+++ b/flag.c
@@ -176,6 +176,19 @@ static int flag_ncp87_modify_attrs(char *name, uint32 attrs)
   if (flag_current_dhandle(&dhandle))
     return(-1);
 
+  /*
+   * Prefer verified Client32 modify path.  The old INT 21h/F257 modify path
+   * can hang under DOS Client32 for high FLAG bits such as T/P/DI/RI.
+   */
+  {
+    uint16 actual = 0;
+    uint16 hlo = 0;
+    uint16 hhi = 0;
+    if (!c32_ncp87_modify_dos_attributes(name, (uint16)dhandle, attrs,
+                                         &actual, &hlo, &hhi))
+      return(0);
+  }
+
   memset(&req, 0, sizeof(req));
   memset(&repl, 0, sizeof(repl));