--- exp_log.c
+++ exp_log.c
@@ -374,7 +374,7 @@ expDiagChannelOpen(interp,filename)
 	Tcl_DStringAppend(&tsdPtr->diagFilename,filename,-1);
     }
 
-    tsdPtr->diagChannel = Tcl_OpenFileChannel(interp,newfilename,"a",0777);
+    tsdPtr->diagChannel = Tcl_OpenFileChannel(interp,newfilename,"a",0666);
     if (!tsdPtr->diagChannel) {
 	Tcl_DStringFree(&tsdPtr->diagFilename);
 	return TCL_ERROR;
@@ -499,7 +499,7 @@ expLogChannelOpen(interp,filename,append
 	Tcl_DStringAppend(&tsdPtr->logFilename,filename,-1);
     }
 
-    tsdPtr->logChannel = Tcl_OpenFileChannel(interp,newfilename,mode,0777);
+    tsdPtr->logChannel = Tcl_OpenFileChannel(interp,newfilename,mode,0666);
     if (!tsdPtr->logChannel) {
 	Tcl_DStringFree(&tsdPtr->logFilename);
 	return TCL_ERROR;