diff --git a/NOVA/nova_defs.h b/NOVA/nova_defs.h
index 207c1c69..26ba2399 100644
--- a/NOVA/nova_defs.h
+++ b/NOVA/nova_defs.h
@@ -51,7 +51,7 @@
 
 #include "sim_defs.h"                                   /* simulator defns */
 
-#if defined(USE_INT64) || defined(USE_ADDR64)
+#if (defined(USE_INT64) && !defined(ECLIPSE)) || defined(USE_ADDR64)
 #error "Nova does not support 64b values!"
 #endif
 
diff --git a/makefile b/makefile
index e78f32c8..c994c84c 100644
--- a/makefile
+++ b/makefile
@@ -1254,7 +1254,7 @@ ECLIPSE = ${NOVAD}/eclipse_cpu.c ${NOVAD}/eclipse_tt.c ${NOVAD}/nova_sys.c \
 	${NOVAD}/nova_dkp.c ${NOVAD}/nova_dsk.c ${NOVAD}/nova_lp.c \
 	${NOVAD}/nova_mta.c ${NOVAD}/nova_plt.c ${NOVAD}/nova_pt.c \
 	${NOVAD}/nova_clk.c ${NOVAD}/nova_tt1.c ${NOVAD}/nova_qty.c
-ECLIPSE_OPT = -I ${NOVAD} -DECLIPSE
+ECLIPSE_OPT = -I ${NOVAD} -DECLIPSE -DUSE_INT64
 
 
 PDP18BD = ${SIMHD}/PDP18B