diff --git a/doc/Doxyfile.in b/doc/Doxyfile.in
--- a/doc/Doxyfile.in
+++ b/doc/Doxyfile.in
@@ -102,7 +102,7 @@
 EXAMPLE_PATTERNS       = 
 EXAMPLE_RECURSIVE      = NO
 IMAGE_PATH             = @abs_top_srcdir@/doc/images \
-		       	 @abs_top_builddir@/doc/gen-images
+                         @abs_top_builddir@/doc/gen-images
 INPUT_FILTER           = 
 FILTER_PATTERNS        = 
 FILTER_SOURCE_FILES    = NO