diff --git a/src/softIoc/Makefile b/src/softIoc/Makefile
index 7a833fe0f..21eafa983 100644
--- a/src/softIoc/Makefile
+++ b/src/softIoc/Makefile
@@ -17,7 +17,7 @@ softIoc_DBD += dlload.dbd
 softIoc_DBD += system.dbd
 
 ABS_INSTALL_DIR = $(shell $(PERL) $(TOOLS)/fullPathName.pl -e $(INSTALL_LOCATION))
-USR_CXXFLAGS += -DEPICS_BASE=$(ABS_INSTALL_DIR)
+USR_CXXFLAGS += -DEPICS_BASE="$(ABS_INSTALL_DIR)"
 
 softIoc_SRCS += softIoc_registerRecordDeviceDriver.cpp
 softIoc_SRCS_DEFAULT += softMain.cpp