diff --git a/cde/programs/dtfile/Imakefile b/cde/programs/dtfile/Imakefile
index 039efe9d1..51a6ad6a5 100644
--- a/cde/programs/dtfile/Imakefile
+++ b/cde/programs/dtfile/Imakefile
@@ -39,6 +39,7 @@ EXTRA_INCLUDES = -I/usr/include/freetype2
 
 #if defined(BSDArchitecture)
 EXTRA_INCLUDES = -I$(XPROJECTROOT)/include/freetype2
+EXTRA_DEFINES = -DFILE_MAP_OPTIMIZE
 #endif
 
 SRCS =  ChangeDir.c     ChangeDirP.c    Command.c       Common.c \