diff --git a/src/sysnet/comsat.585 b/src/sysnet/comsat.585
index 11adc1ce..6026a9f3 100644
--- a/src/sysnet/comsat.585
+++ b/src/sysnet/comsat.585
@@ -155,6 +155,13 @@ T==:U1	; Alternate names for smashable ACs.
 TT==:U2 ; This is mostly for NETWRK/RESOLV.
 IFE U2-OC,.ERR RESOLV temp ACs lose!!
 
+	; Check if SYSTEM;HOSTS3 has been updated in EQVCHK, to ensure
+	; that current addresses are used for hosts in NAMES.
+	; Note: this only has the intended effect for hosts/addresses
+	; in SYSTEM;HOSTS3. Some other mechanism would be needed for
+	; hosts/addresses from DNS or HOSTAB servers.
+IFNDEF $$H3CHK,$$H3CHK==1
+
 $$DQ==1		; Domain interface code in use (mostly for NETRTS)
 $$DQRN==1	; Use RENMWO hack to cut down on resolver overhead
 ;; These are IFNDEFs for now so that I can play with them without
@@ -2963,9 +2970,11 @@ EQVCHK:	PUSHAE P,[A,B]
 	SYSCAL RFDATE,[CIMM DKIC ? CRET A]	; Get creation time.
 	 JSR SYSLOS
 	CAMN A,EQVTIM		; Compare with time of last file gobbled
-	 JRST EQVCH9		; OK, still same
+IFE $$H3CHK, JRST EQVCH9		; OK, still same
+.ELSE    JRST EQVCH2		; but need to check EQV vs HOSTS3
 	EXCH A,EQVTIM		; Not same!!! Store new, get old time.
 	JUMPN A,EQVCH3		; Jump if cause is new ASCII file.
+IFN $$H3CHK, EQVCH2:
 	;; Initialization, see if really need to re-compile.
 	;; Get creation time for existing bin file and compare.
 	.IOPUSH DKIC,		; Save chan.
@@ -2977,7 +2986,8 @@ EQVCHK:	PUSHAE P,[A,B]
 	 JSR SYSLOS
 	.IOPOP DKIC,
 	CAML A,EQVTIM		; Bin created before ascii file?
-	 JRST EQVCH9		; Nope, created after, win!  Needn't compile.
+IFE $$H3CHK, JRST EQVCH9		; Nope, created after, win!  Needn't compile.
+.ELSE    JRST EQVCH5		; but need to check EQV vs HOSTS3
 	;; New ASCII file has appeared, must try to compile it.
 EQVCH3:	CALL EQVGOB		; Attempt compile
 	 CAIA			;   Compilation lost?
@@ -2993,6 +3003,25 @@ EQVCH7:	STAT (,("Note: EQV file compiled."))
 EQVCH9:	POPAE P,[B,A]
 	.CLOSE DKIC,
 	RET
+IFN $$H3CHK,[
+;; Double-check routine, for when normally no recompilation would be needed.
+;; Come here if NAMES hasn't been updated since last check,
+;; or if EQV file created after NAMES file, with A/ EQV creation time.
+;; Now compare EQV creation time with HOSTS3 creation time, and recompile
+;; if HOSTS3 has been updated. (Otherwise we may keep using old host addresses.)
+EQVCH5:	.IOPUSH DKIC,		; Save channel.
+	MOVE B,A		; Save EQV creation time. <
+	MOVEI A,[ SIXBIT 'DSK' ? SIXBIT 'SYSBIN' ? SIXBIT 'HOSTS3' ? SIXBIT '>' ]
+	CALL OPNFLI		; General purpose opener
+	 JRST EQVCH9		; We'll catch it when it appears again.
+	SYSCAL RFDATE,[CIMM DKIC ? CRET A ] ; Get creation date
+	 JSR SYSLOS
+	.IOPOP DKIC,
+	CAML B,A		; H3 created before EQV?
+	 JRST EQVCH9		; No need to do anything.
+	STAT (,("Note: HOSTS3 file updated, need to recompile EQV file"))
+	JRST EQVCH3		; H3 created after, so need to recompile
+]
 
 ;;; EQVBIN/EQVGET - Slurp binary up into core.