diff --git a/Tools/Makefile.preamble b/Tools/Makefile.preamble
index 3a0671a1c..224e3c1a8 100644
--- a/Tools/Makefile.preamble
+++ b/Tools/Makefile.preamble
@@ -36,7 +36,7 @@
 #
 
 # Additional flags to pass to the preprocessor
-ADDITIONAL_CPPFLAGS += -DHAVE_LIBXML=$(HAVE_LIBXML)
+ADDITIONAL_CPPFLAGS +=
 
 # Additional flags to pass to the Objective-C compiler
 ADDITIONAL_OBJCFLAGS += -Wall
diff --git a/Tools/autogsdoc.m b/Tools/autogsdoc.m
index c1a999caa..73fa0d653 100644
--- a/Tools/autogsdoc.m
+++ b/Tools/autogsdoc.m
@@ -381,7 +381,7 @@ main(int argc, char **argv, char **env)
   [NSProcessInfo initializeWithArguments: argv count: argc environment: env];
 #endif
 
-#ifdef HAVE_LIBXML == 0
+#ifndef HAVE_LIBXML
   NSLog(@"ERROR: The GNUstep Base Library was built\n"
 @"        without an available libxml library. Autogsdoc needs the libxml\n"
 @"        library to function. Aborting");