diff --git a/lib/Makefile.m32 b/lib/Makefile.m32
index 17085cdc15cf3b5d1d5debc3fdb96e6253233073..76145917d929f77c9f020a25d2df0879e6a01b88 100644
--- a/lib/Makefile.m32
+++ b/lib/Makefile.m32
@@ -50,6 +50,9 @@ endif
 ifdef SSPI
   CFLAGS += -DUSE_WINDOWS_SSPI
 endif
+ifdef IPV6
+  CFLAGS += -DENABLE_IPV6
+endif
 COMPILE = $(CC) $(INCLUDES) $(CFLAGS)
 
 # Makefile.inc provides the CSOURCES and HHEADERS defines
diff --git a/src/Makefile.m32 b/src/Makefile.m32
index 7bae329417bbfbac9190a9eedac29e3418c0cbce..49f070ad628f5ad5491281d63ccd50553ba83593 100644
--- a/src/Makefile.m32
+++ b/src/Makefile.m32
@@ -58,6 +58,9 @@ endif
 ifdef SSPI
   CFLAGS += -DUSE_WINDOWS_SSPI
 endif
+ifdef IPV6
+  CFLAGS += -DENABLE_IPV6
+endif
 curl_LDADD += -lwsock32 -lws2_32 -lwinmm -L$(ZLIB_PATH) -lz
 
 # Makefile.inc provides the CSOURCES and HHEADERS defines