diff --git a/lua/wincent/commandt/lib/Makefile b/lua/wincent/commandt/lib/Makefile
index 1571b37a..11950508 100644
--- a/lua/wincent/commandt/lib/Makefile
+++ b/lua/wincent/commandt/lib/Makefile
@@ -13,9 +13,9 @@ ifeq ($(LBITS),64)
 	CCFLAGS += -DMMAP_SLAB_SIZE_CONF=137438953472
 else
 	# 32 M candidates.
-	CCFLAGS += MAX_FILES_CONF=33554432
+	CCFLAGS += -DMAX_FILES_CONF=33554432
 	# 32 GB.
-	CCFLAGS += MMAP_SLAB_SIZE_CONF=34359738368
+	CCFLAGS += -DMMAP_SLAB_SIZE_CONF=34359738368
 endif
 
 ifdef DEBUG