diff --git a/lang/m2/libm2/Streams.mod b/lang/m2/libm2/Streams.mod
index 7e123bacb..a40133757 100644
--- a/lang/m2/libm2/Streams.mod
+++ b/lang/m2/libm2/Streams.mod
@@ -17,8 +17,7 @@ IMPLEMENTATION MODULE Streams;
   FROM	SYSTEM IMPORT	BYTE, ADR;
   FROM	Epilogue IMPORT	CallAtEnd;
   FROM	Storage IMPORT	Allocate, Available;
-  FROM	StripUnix IMPORT
-			open, close, lseek, read, write, creat, ioctl;
+  IMPORT StripUnix;
 
   CONST BUFSIZ = 1024;	(* tunable *)
   TYPE	IOB = RECORD
@@ -82,17 +81,17 @@ IMPLEMENTATION MODULE Streams;
                 buf[HIGH(filename)+2] := BYTE(0C);
 	END;
 	IF (mode = reading) THEN
-		fd := open(ADR(stream^.buf), 0);
+		fd := StripUnix.open(ADR(stream^.buf), 0);
 	ELSE
 		fd := -1;
 		IF (mode = appending) THEN
-			fd := open(ADR(stream^.buf), 1);
+			fd := StripUnix.open(ADR(stream^.buf), 1);
 			IF fd >= 0 THEN
-				IF (lseek(fd, 0D , 2) < 0D) THEN ; END;
+				IF (StripUnix.lseek(fd, 0D , 2) < 0D) THEN ; END;
 			END;
 		END;
 		IF fd < 0 THEN
-			fd := creat(ADR(stream^.buf), 666B);
+			fd := StripUnix.creat(ADR(stream^.buf), 666B);
 		END;
 	END;
 	IF fd < 0 THEN
@@ -153,7 +152,7 @@ IMPLEMENTATION MODULE Streams;
 		IF (cnt > 0) THEN
 			cnt1 := cnt;
 			cnt := 0;
-			IF write(fildes, ADR(buf), cnt1) < 0 THEN END;
+			IF StripUnix.write(fildes, ADR(buf), cnt1) < 0 THEN END;
 		END;
 	END;
   END FlushStream;
@@ -165,7 +164,7 @@ IMPLEMENTATION MODULE Streams;
 		IF stream^.mode # reading THEN
 			FlushStream(stream, result);
 		END;
-		IF close(stream^.fildes) < 0 THEN ; END;
+		IF StripUnix.close(stream^.fildes) < 0 THEN ; END;
 		freestruct(stream);
 	ELSE
 		result := nostream;
@@ -212,7 +211,7 @@ IMPLEMENTATION MODULE Streams;
 			IF stream = InputStream THEN
 				FlushLineBuffers();
 			END;
-			maxcnt := read(fildes, ADR(buf), bufferedcnt);
+			maxcnt := StripUnix.read(fildes, ADR(buf), bufferedcnt);
 			cnt := 1;
 			IF maxcnt <= 0 THEN
 				eof := TRUE;
@@ -335,7 +334,7 @@ IMPLEMENTATION MODULE Streams;
 		RETURN;
 	END;
 	IF (s^.mode # reading) THEN FlushStream(s, result); END;
-	position := lseek(s^.fildes, 0D, 1);
+	position := StripUnix.lseek(s^.fildes, 0D, 1);
 	IF position < 0D THEN
 		result := illegaloperation;
 		RETURN;
@@ -360,7 +359,7 @@ IMPLEMENTATION MODULE Streams;
 		s^.eof := FALSE;
 	END;
 	IF s^.mode = appending THEN
-		currpos := lseek(s^.fildes, 0D, 1);
+		currpos := StripUnix.lseek(s^.fildes, 0D, 1);
 		IF currpos < 0D THEN
 			result := illegaloperation;
 			RETURN;
@@ -370,7 +369,7 @@ IMPLEMENTATION MODULE Streams;
 		result := illegaloperation;
 		RETURN;
 	END;
-	currpos := lseek(s^.fildes, position, 0);
+	currpos := StripUnix.lseek(s^.fildes, position, 0);
 	IF currpos < 0D THEN
 		result := illegaloperation;
 		RETURN;
@@ -379,21 +378,15 @@ IMPLEMENTATION MODULE Streams;
   END SetPosition;
 
   PROCEDURE isatty(stream: Stream; VAR result: StreamResult): BOOLEAN;
-    VAR buf: ARRAY[1..100] OF CHAR;
   BEGIN
 	IF (stream = NIL) OR (stream^.kind = none) THEN
 		result := nostream;
 		RETURN FALSE;
 	END;
-#ifdef __USG
-	RETURN ioctl(stream^.fildes, INTEGER(ORD('T') * 256 + 1), ADR(buf)) >= 0;
-#else
-#ifdef __BSD4_2
-	RETURN ioctl(stream^.fildes, INTEGER(ORD('t') * 256 + 8 + 6*65536 + 40000000H), ADR(buf)) >= 0;
-#else
-	RETURN ioctl(stream^.fildes, INTEGER(ORD('t') * 256 + 8), ADR(buf)) >= 0;
-#endif
-#endif
+	IF (StripUnix.isatty(stream^.fildes) = 0) THEN
+		RETURN FALSE;
+	END;
+	RETURN TRUE;
   END isatty;
 
   PROCEDURE InitStreams;
diff --git a/lang/m2/libm2/StripUnix.def b/lang/m2/libm2/StripUnix.def
index 8a016d813..3587dd793 100644
--- a/lang/m2/libm2/StripUnix.def
+++ b/lang/m2/libm2/StripUnix.def
@@ -21,6 +21,7 @@ DEFINITION MODULE StripUnix;
   (* Sys5 *) PROCEDURE fcntl(fildes, request, arg: INTEGER) : INTEGER;
   PROCEDURE getpid() : INTEGER;
   PROCEDURE ioctl(fildes, request: INTEGER; arg: ADDRESS) : INTEGER;
+  PROCEDURE isatty(fildes: INTEGER) : INTEGER;
   PROCEDURE lseek(fildes: INTEGER; offset: LONGINT; whence: INTEGER) : LONGINT;
   PROCEDURE open(path: ADDRESS; oflag: INTEGER) : INTEGER;
   PROCEDURE read(fildes: INTEGER;
diff --git a/lang/m2/libm2/Unix.def b/lang/m2/libm2/Unix.def
index 12ce95051..f246160bb 100644
--- a/lang/m2/libm2/Unix.def
+++ b/lang/m2/libm2/Unix.def
@@ -79,6 +79,7 @@ DEFINITION MODULE Unix;
   PROCEDURE getgid() : INTEGER;
   PROCEDURE getegid() : INTEGER;
   PROCEDURE ioctl(fildes, request: INTEGER; arg: ADDRESS) : INTEGER;
+  PROCEDURE isatty(fildes: INTEGER) : INTEGER;
   PROCEDURE stty(fildes: INTEGER; buf: ADDRESS) : INTEGER;
   PROCEDURE gtty(fildes: INTEGER; buf: ADDRESS) : INTEGER;
   PROCEDURE kill(pid, sig: INTEGER) : INTEGER;