diff --git a/App/tools/driver.makefile b/App/tools/driver.makefile
index 42fc9be..523d9f2 100644
--- a/App/tools/driver.makefile
+++ b/App/tools/driver.makefile
@@ -338,7 +338,7 @@ ${CONFIG}/CONFIG:
 	@echo "ERROR: EPICS release ${EPICSVERSION} not installed on this host."
 
 # Some TOP and EPICS_BASE tweeking necessary to work around release check in 3.14.10+.
-EB=${EPICS_BASE}
+EB:=${EPICS_BASE}
 TOP:=${EPICS_BASE}
 -include ${CONFIG}/CONFIG
 BASE_CPPFLAGS=