diff --git a/m4/curl-compilers.m4 b/m4/curl-compilers.m4
index 20bdbd706..c1ae6a559 100644
--- a/m4/curl-compilers.m4
+++ b/m4/curl-compilers.m4
@@ -5,7 +5,7 @@
 #                            | (__| |_| |  _ <| |___
 #                             \___|\___/|_| \_\_____|
 #
-# Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
+# Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
 #
 # This software is licensed as described in the file COPYING, which
 # you should have received as part of this distribution. The terms
@@ -1299,15 +1299,6 @@ AC_DEFUN([CURL_CHECK_CURLDEBUG], [
       want_curldebug="no"
     fi
   fi
-  #
-  if test "$want_curldebug" = "yes"; then
-    CPPFLAGS="-DCURLDEBUG $CPPFLAGS"
-    squeeze CPPFLAGS
-  fi
-  if test "$want_debug" = "yes"; then
-    CPPFLAGS="-DDEBUGBUILD $CPPFLAGS"
-    squeeze CPPFLAGS
-  fi
 ])
 
 
diff --git a/m4/curl-confopts.m4 b/m4/curl-confopts.m4
index 6dcd0f1a6..ad6acd8f0 100644
--- a/m4/curl-confopts.m4
+++ b/m4/curl-confopts.m4
@@ -114,6 +114,7 @@ AC_HELP_STRING([--disable-curldebug],[Disable curl debug memory tracking]),
       dnl as a request to disable curldebug.
       if test "$want_debug" = "yes"; then
         AC_MSG_RESULT([(assumed) yes])
+        AC_DEFINE(CURLDEBUG, 1, [to enable curl debug memory tracking])
       else
         AC_MSG_RESULT([no])
       fi
@@ -130,6 +131,7 @@ AC_HELP_STRING([--disable-curldebug],[Disable curl debug memory tracking]),
       dnl --disable-curldebug had been given setting shell variable
       dnl want_curldebug to 'no'.
       want_curldebug="yes"
+      AC_DEFINE(CURLDEBUG, 1, [to enable curl debug memory tracking])
       AC_MSG_RESULT([yes])
       ;;
   esac
@@ -164,6 +166,7 @@ AC_HELP_STRING([--disable-debug],[Disable debug build options]),
     *)
       dnl --enable-debug option used
       want_debug="yes"
+      AC_DEFINE(DEBUGBUILD, 1, [enable debug build options])
       ;;
   esac
   AC_MSG_RESULT([$want_debug])