diff --git a/src/connect.c b/src/connect.c
index dec95b8..59e408f 100644
--- a/src/connect.c
+++ b/src/connect.c
@@ -1896,7 +1896,7 @@ static int do_set_file_info(NW_PATH *nwpath, FUNC_SEARCH *fs)
   if (!stat(unname, &statb)) {
     if (S_ISFIFO(statb.st_mode) || (voloptions&VOL_OPTION_IS_PIPE))
       return(0); /* do nothing but report OK */
-    if (!tru_eff_rights_exists(nwpath->volume, unname, &statb, TRUSTEE_M))
+    if (tru_eff_rights_exists(nwpath->volume, unname, &statb, TRUSTEE_M))
       result=-0x8c;  /* no modify rights */
   } else result=-0xff;
   if (!result) {
diff --git a/src/namspace.c b/src/namspace.c
index 105d297..5d87cc6 100644
--- a/src/namspace.c
+++ b/src/namspace.c
@@ -2643,7 +2643,7 @@ static int nw_modify_file_dir(int namespace,
         xfree(uname);
         return(0); /* do nothing but report OK */
       }
-      if (!tru_eff_rights_exists(dbe->nwpath.volume, uname, stb, 
+      if (tru_eff_rights_exists(dbe->nwpath.volume, uname, stb, 
            TRUSTEE_M))
         result=-0x8c;  /* no modify rights */
       if (!result && (infomask & DOS_MSK_ATTRIBUTE)){
@@ -2651,7 +2651,7 @@ static int nw_modify_file_dir(int namespace,
                                    GET_32(dmi->attributes));
       }
       if ( (!result) && (infomask & DOS_MSK_INHERIT_RIGHTS)
-         && tru_eff_rights_exists(dbe->nwpath.volume, uname, stb, TRUSTEE_A) ) {
+         && !tru_eff_rights_exists(dbe->nwpath.volume, uname, stb, TRUSTEE_A) ) {
         int mask       = tru_get_inherited_mask(dbe->nwpath.volume, uname, stb);
         int grantmask  = GET_16(dmi->rightsgrantmask);
         int revokemask = GET_16(dmi->rightsrevokemask);
@@ -2663,7 +2663,7 @@ static int nw_modify_file_dir(int namespace,
       }
       if ((!result) && (infomask & DOS_MSK_MAX_SPACE)) {
         if (S_ISDIR(stb->st_mode)) {
-          if (!tru_eff_rights_exists(dbe->nwpath.volume, uname, stb, TRUSTEE_M))
+          if (tru_eff_rights_exists(dbe->nwpath.volume, uname, stb, TRUSTEE_M))
             result=-0x8c;
           else
             result=nsp_set_dir_quota_metadata((const char*)uname,
diff --git a/src/nwattrib.c b/src/nwattrib.c
index b227864..0096e5b 100644
--- a/src/nwattrib.c
+++ b/src/nwattrib.c
@@ -221,7 +221,7 @@ static int set_nw_attrib(
   int voloptions=get_volume_options(volume);
   if (voloptions & VOL_OPTION_IS_PIPE)
      return(0); /* we return with no error */
-  if (!tru_eff_rights_exists(volume, unixname, stb, TRUSTEE_M))
+  if (tru_eff_rights_exists(volume, unixname, stb, TRUSTEE_M))
      return(-0x8c); /* no modify rights */
   if (!(voloptions & VOL_OPTION_ATTRIBUTES)) {
     if (!(get_unix_eff_rights(stb) & W_OK)) {