diff --git a/GNUmakefile b/GNUmakefile
index 1aa1a1d..fd998a8 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -55,7 +55,7 @@ libobjc_HEADER_FILES = \
 	objc-api.h
 endif
 
-ifeq ($(tdd), yes)
+ifneq ($(tdd), no)
 libobjc_CPPFLAGS += -DTYPE_DEPENDENT_DISPATCH
 endif
 
diff --git a/Makefile b/Makefile
index 8bf86ad..8a4ffcb 100644
--- a/Makefile
+++ b/Makefile
@@ -5,6 +5,7 @@ VERSION = 4
 #CC=clang
 
 CFLAGS += -std=c99
+CPPFLAGS += -DTYPE_DEPENDENT_DISPATCH
 
 #LIB_DIR=/usr/local/GNUstep/Local/Library/Libraries/
 #HEADER_DIR=/usr/local/GNUstep/Local/Library/Headers