diff --git a/lib/Makefile.vc6 b/lib/Makefile.vc6
index 597e59393..a863a0b3e 100644
--- a/lib/Makefile.vc6
+++ b/lib/Makefile.vc6
@@ -105,7 +105,7 @@ WINDOWS_SDK_PATH = "$(PROGRAMFILES)\Microsoft SDK"
 
 CCNODBG    = cl.exe /O2 /DNDEBUG
 CCDEBUG    = cl.exe /Od /Gm /Zi /D_DEBUG /GZ
-CFLAGSSSL  = /DUSE_SSLEAY /I "$(OPENSSL_PATH)/inc32" /I "$(OPENSSL_PATH)/inc32/openssl"
+CFLAGSSSL  = /DUSE_SSLEAY /DUSE_OPENSSL /I "$(OPENSSL_PATH)/inc32" /I "$(OPENSSL_PATH)/inc32/openssl"
 CFLAGSSSH2 = /DUSE_LIBSSH2 /DCURL_DISABLE_LDAP /DHAVE_LIBSSH2 /DHAVE_LIBSSH2_H /DLIBSSH2_WIN32 /DLIBSSH2_LIBRARY /I "$(LIBSSH2_PATH)/include"
 CFLAGSZLIB = /DHAVE_ZLIB_H /DHAVE_ZLIB /DHAVE_LIBZ /I "$(ZLIB_PATH)"
 CFLAGS     = /I. /I../include /nologo /W3 /GX /DWIN32 /YX /FD /c /DBUILDING_LIBCURL /D_BIND_TO_CURRENT_VCLIBS_VERSION=1