diff --git a/aegisub/docs/doxygen/doxyfile b/aegisub/docs/doxygen/doxyfile
index 72c86f664..44a2a8185 100644
--- a/aegisub/docs/doxygen/doxyfile
+++ b/aegisub/docs/doxygen/doxyfile
@@ -215,7 +215,29 @@ EXPAND_ONLY_PREDEF     = YES
 SEARCH_INCLUDES        = YES
 INCLUDE_PATH           = 
 INCLUDE_FILE_PATTERNS  = 
-PREDEFINED             = 
+PREDEFINED             =
+PREDEFINED             +=	\
+							WITH_PORTAUDIO \
+							WITH_ALSA \
+							WITH_AUTO4_LUA \
+							WITH_AUTOMATION \
+							WITH_AVISYNTH \
+							WITH_CSRI \
+							WITH_DIRECTSOUND \
+							WITH_FFMPEGSOURCE \
+							WITH_FONTCONFIG \
+							WITH_FREETYPE2 \
+							WITH_HUNSPELL \
+							WITH_LIBASS \
+							WITH_OLD_HUNSPELL \
+							WITH_OPENAL \
+							WITH_PORTAUDIO \
+							WITH_PORTAUDIO2 \
+							WITH_PULSEAUDIO \
+							WITH_QUICKTIME \
+							WITH_STARTUPLOG \
+							WITH_UNIVCHARDET
+
 PREDEFINED             += WXUNUSED(x)= 
 EXPAND_AS_DEFINED      = 
 SKIP_FUNCTION_MACROS   = YES