diff --git a/sc2/build/unix/build.docs b/sc2/build/unix/build.docs
index 7290ee735..b3b8bcfd8 100644
--- a/sc2/build/unix/build.docs
+++ b/sc2/build/unix/build.docs
@@ -122,7 +122,8 @@ Information about programs used should be supplied in the following form:
     done configuring.
   - PROG_${PROGRAM}_DETECT (optional)
     A command to be executed which should return 0 if the program is present
-    on the system, or 1 otherwise. If not supplied, 'type' is
+    on the system, 1 if it is not present, or 2 to fallback to the default
+    detection. If no detect function was set, or it returned 2, 'type' is
     used to check for the program in the path.
     This command may include a shell command that modifies any of the
     variables PROG_${PROGRAM}_FILE, PROG_${PROGRAM}_ACTION, or
@@ -156,9 +157,10 @@ Information about libraries used should be supplied in the following form:
     is used.
   - PROG_${LIB}_DETECT (optional)
     A command to be executed which should return 0 if the library is present
-    on the system, or 1 otherwise. If not supplied, an attempt is
-    made to compile and link an empty C program with the flags as in
-    LIB_${LIB}_CFLAGS and LIB_${LIB}_LDFLAGS.
+    on the system, 1 if it is not present, or 2 to fallback to the default
+    detection. If no detect function was set, or it returned 2,
+    an attempt is made to compile and link an empty C program with
+    the flags as in LIB_${LIB}_CFLAGS and LIB_${LIB}_LDFLAGS.
     This command may include a shell command that modifies any of the
     variables PROG_${LIB}_CFLAGS, PROG_${LIB}_LDFLAGS, or
     PROG_${LIB}_VERSION.
diff --git a/sc2/build/unix/config_functions b/sc2/build/unix/config_functions
index e5a96fa85..5e6a29240 100644
--- a/sc2/build/unix/config_functions
+++ b/sc2/build/unix/config_functions
@@ -194,17 +194,30 @@ have_program() {
 		$TEMP_DETECT
 		# NB. TEMP_DETECT should make sure PROG_${PROG}_VERSION and
                 # PROG_${PROG}_FILE are set.
-		if [ $? -ne 0 ]; then
-			eval "PROG_${PROG}_PRESENT"=1
-			build_message "$TEMP_NAME not found."
-			return 1
-		fi
+		case $? in
+			0)  # Program found
+				eval "PROG_${PROG}_PRESENT"=0
+				;;
+			1)  # Lib not found
+				eval "PROG_${PROG}_PRESENT"=1
+				;;
+			2)  # Use default detection
+				;;
+		esac
 	fi
 
-	TEMP_FILE=`evalVar PROG_${PROG}_FILE`
-
-	type "${TEMP_FILE%% *}" > /dev/null 2>&1
-	if [ $? -ne 0 ]; then
+	eval TEMP_PRESENT="\$PROG_${PROG}_PRESENT"
+	if [ -z "$TEMP_PRESENT" ]; then
+		TEMP_FILE=`evalVar PROG_${PROG}_FILE`
+		type "${TEMP_FILE%% *}" > /dev/null 2>&1
+		if [ $? -eq 0 ]; then
+			# Program found
+			eval "PROG_${PROG}_PRESENT"=0
+		fi
+	fi
+	
+	eval TEMP_PRESENT="\$PROG_${PROG}_PRESENT"
+	if [ -z "$TEMP_PRESENT" ]; then
 		eval "PROG_${PROG}_PRESENT"=1
 		build_message "$TEMP_NAME not found."
 		return 1
@@ -262,14 +275,27 @@ have_library() {
 	
 	TEMP_DETECT=`evalVar LIB_${LIB}_DETECT`
 	if [ -n "$TEMP_DETECT" ]; then
-		$TEMP_DETECT
 		TEMP_DEPEND_PROG=`evalVar LIB_${LIB}_DEPEND_DETECT_PROG`
 		TEMP_DEPEND_LIB=`evalVar LIB_${LIB}_DEPEND_DETECT_LIB`
 		detect_dependencies_program "$TEMP_DEPEND_PROG"
 		detect_dependencies_library "$TEMP_DEPEND_LIB"
+		$TEMP_DETECT
 		# NB. TEMP_DETECT should make sure PROG_$LIB_VERSION is set.
 		# return value of $TEMP_DETECT is used below.
-	else
+		case $? in
+			0)  # Lib found
+				eval "LIB_${LIB}_PRESENT"=0
+				;;
+			1)  # Lib not found
+				eval "LIB_${LIB}_PRESENT"=1
+				;;
+			2)  # Use default detection
+				;;
+		esac
+	fi
+
+	eval TEMP_PRESENT="\$LIB_${LIB}_PRESENT"
+	if [ -z "$TEMP_PRESENT" ]; then
 		TEMP_CFLAGS=`evalVar LIB_${LIB}_CFLAGS`
 		TEMP_LDFLAGS=`evalVar LIB_${LIB}_LDFLAGS`
 
@@ -280,9 +306,14 @@ int main(int argc, char *argv[]) {
 	return 0;
 }
 EOF
-	fi  # TEMP_DETECT not defined
+		if [ $? -eq 0 ]; then
+			# Build successful
+			eval "LIB_${LIB}_PRESENT"=0
+		fi
+	fi
 	
-	if [ $? -ne 0 ]; then
+	eval TEMP_PRESENT="\$LIB_${LIB}_PRESENT"
+	if [ -z "$TEMP_PRESENT" ]; then
 		eval "LIB_${LIB}_PRESENT"=1
 		build_message "$TEMP_NAME not found."
 		return 1
@@ -548,7 +579,7 @@ try_pkgconfig_prog() {
 		eval PROG_${PROG}_VERSION=\$TEMP_VERSION
 		return 0
 	else
-		return 1
+		return 2
 	fi
 }
 
@@ -582,9 +613,10 @@ try_pkgconfig_lib() {
 		eval LIB_${LIB}_VERSION=\$TEMP_VERSION
 		eval LIB_${LIB}_CFLAGS=\$TEMP_CFLAGS
 		eval LIB_${LIB}_LDFLAGS=\$TEMP_LDFLAGS
-		return 0
+		return 2  # Force testing using the new CFLAGS and LDFLAGS
+		#return 0
 	else
-		return 1
+		return 2
 	fi
 }
 
diff --git a/sc2/build/unix/config_proginfo b/sc2/build/unix/config_proginfo
index 0cdb4e91d..a1a7b1351 100644
--- a/sc2/build/unix/config_proginfo
+++ b/sc2/build/unix/config_proginfo
@@ -132,7 +132,7 @@ case "$OSNAME" in
 		LIB_SDL_VERSION='$(sdl11-config --version)'
 		;;
 	Darwin)
-		LIB_SDL_CFLAGS='-I/System/Library/Frameworks/SDL.framework/Headers -I/Library/Frameworks/SDL.framework/Headers -I$HOME/Library/Frameworks/SDL.framework/Headers'
+		LIB_SDL_CFLAGS=''
 		LIB_SDL_LDFLAGS='-framework SDL -framework Cocoa -lobjc'
 		LIB_SDL_VERSION=$(echo \
                       "SDL_MAJOR_VERSION.SDL_MINOR_VERSION.SDL_PATCHLEVEL" | \
@@ -158,7 +158,7 @@ LIB_SDL_mixer_VERSION=""
 LIB_SDL_image_NAME="SDL_image"
 case "$OSNAME" in
 	Darwin)
-		LIB_SDL_image_CFLAGS='-I/System/Library/Frameworks/SDL_image.framework/Headers -I/Library/Frameworks/SDL_image.framework/Headers -I$HOME/Library/Frameworks/SDL_image.framework/Headers'
+		LIB_SDL_image_CFLAGS=''
 		LIB_SDL_image_LDFLAGS="-framework SDL_image"
 	;;
 	*)
@@ -176,9 +176,13 @@ case "$OSNAME" in
 	FreeBSD|OpenBSD)
 		LIB_openal_LDFLAGS="-L/usr/local/lib -pthread -lopenal"
 		;;
-	MINGW32*) 
+	MINGW32*)
 		LIB_openal_LDFLAGS="-lopenal32"
 		;;
+	Darwin)
+		LIB_openal_CFLAGS=''
+		LIB_openal_LDFLAGS="-framework OpenAL"
+		;;
 	*)
 		LIB_openal_LDFLAGS="-lopenal"
 		;;
diff --git a/sc2/src/port.h b/sc2/src/port.h
index de88bb862..65808510d 100644
--- a/sc2/src/port.h
+++ b/sc2/src/port.h
@@ -137,6 +137,20 @@ iswgraph(wint_t wc)
 }
 #endif
 
+// Use SDL_INCLUDE to portably include the SDL files from the right
+// location. TODO: Where SDL_H is located could be detected from the build
+// script.
+#ifdef APPLE
+#	define HAVE_SDL_SDL_H
+#else
+#	define HAVE_SDL_H
+#endif
+#ifdef HAVE_SDL_H
+#	define SDL_INCLUDE(file) <file>
+#elif defined(HAVE_SDL_SDL_H)
+#	define SDL_INCLUDE(file) <SDL/file>
+#endif
+
 #endif  /* _PORT_H */
 
 
diff --git a/sc2/src/sc2code/libs/graphics/sdl/bbox.c b/sc2/src/sc2code/libs/graphics/sdl/bbox.c
index b1904728a..62cf62abe 100644
--- a/sc2/src/sc2code/libs/graphics/sdl/bbox.c
+++ b/sc2/src/sc2code/libs/graphics/sdl/bbox.c
@@ -1,4 +1,5 @@
-#include "SDL.h"
+#include "port.h"
+#include SDL_INCLUDE(SDL.h)
 #include "bbox.h"
 
 TFB_BoundingBox TFB_BBox;
diff --git a/sc2/src/sc2code/libs/graphics/sdl/canvas.c b/sc2/src/sc2code/libs/graphics/sdl/canvas.c
index 08e7fad7e..3d6746154 100644
--- a/sc2/src/sc2code/libs/graphics/sdl/canvas.c
+++ b/sc2/src/sc2code/libs/graphics/sdl/canvas.c
@@ -1,4 +1,5 @@
-#include "SDL.h"
+#include "port.h"
+#include SDL_INCLUDE(SDL.h)
 #include "sdl_common.h"
 #include "libs/graphics/gfx_common.h"
 #include "libs/graphics/sdl/primitives.h"
diff --git a/sc2/src/sc2code/libs/graphics/sdl/rotozoom.h b/sc2/src/sc2code/libs/graphics/sdl/rotozoom.h
index ceedb7731..728fd429b 100644
--- a/sc2/src/sc2code/libs/graphics/sdl/rotozoom.h
+++ b/sc2/src/sc2code/libs/graphics/sdl/rotozoom.h
@@ -18,7 +18,8 @@
 #define M_PI	3.141592654
 #endif
 
-#include "SDL.h"
+#include "port.h"
+#include SDL_INCLUDE(SDL.h)
 
 
 /* ---- Defines */
diff --git a/sc2/src/sc2code/libs/graphics/sdl/sdl_common.h b/sc2/src/sc2code/libs/graphics/sdl/sdl_common.h
index 2b7ab02d7..7b18cc6f8 100644
--- a/sc2/src/sc2code/libs/graphics/sdl/sdl_common.h
+++ b/sc2/src/sc2code/libs/graphics/sdl/sdl_common.h
@@ -19,9 +19,10 @@
 #ifndef SDL_COMMON_H
 #define SDL_COMMON_H
 
-#include "SDL.h"
-#include "SDL_image.h"
-#include "SDL_byteorder.h"
+#include "port.h"
+#include SDL_INCLUDE(SDL.h)
+#include SDL_INCLUDE(SDL_image.h)
+#include SDL_INCLUDE(SDL_byteorder.h)
 
 #include "libs/graphics/gfxintrn.h"
 #include "libs/graphics/tfb_draw.h"
diff --git a/sc2/src/sc2code/libs/graphics/sdl/sdluio.c b/sc2/src/sc2code/libs/graphics/sdl/sdluio.c
index 9e21d8857..7f3f66f60 100644
--- a/sc2/src/sc2code/libs/graphics/sdl/sdluio.c
+++ b/sc2/src/sc2code/libs/graphics/sdl/sdluio.c
@@ -2,10 +2,10 @@
 
 #include "port.h"
 #include "libs/uio.h"
-#include "SDL.h"
-#include "SDL_image.h"
-#include "SDL_error.h"
-#include "SDL_rwops.h"
+#include SDL_INCLUDE(SDL.h)
+#include SDL_INCLUDE(SDL_image.h)
+#include SDL_INCLUDE(SDL_error.h)
+#include SDL_INCLUDE(SDL_rwops.h)
 #include "libs/misc.h"
 #include <errno.h>
 #include <string.h>
diff --git a/sc2/src/sc2code/libs/graphics/sdl/sdluio.h b/sc2/src/sc2code/libs/graphics/sdl/sdluio.h
index ab97b2e33..c3178894d 100644
--- a/sc2/src/sc2code/libs/graphics/sdl/sdluio.h
+++ b/sc2/src/sc2code/libs/graphics/sdl/sdluio.h
@@ -3,8 +3,8 @@
 
 #include "port.h"
 #include "libs/uio.h"
-#include "SDL.h"
-#include "SDL_rwops.h"
+#include SDL_INCLUDE(SDL.h)
+#include SDL_INCLUDE(SDL_rwops.h)
 
 SDL_Surface *sdluio_loadImage (uio_DirHandle *dir, const char *fileName);
 int sdluio_seek (SDL_RWops *context, int offset, int whence);
diff --git a/sc2/src/sc2code/libs/input/sdl/keynames.c b/sc2/src/sc2code/libs/input/sdl/keynames.c
index 4acf56e67..234b2d34e 100644
--- a/sc2/src/sc2code/libs/input/sdl/keynames.c
+++ b/sc2/src/sc2code/libs/input/sdl/keynames.c
@@ -1,7 +1,7 @@
-#include <SDL.h>
+#include "port.h"
+#include SDL_INCLUDE(SDL.h)
 #include <string.h>
 #include "keynames.h"
-#include "port.h"
 
 /* This code is adapted from the code in SDL_keysym.h.  Though this
  * would almost certainly be fast if we were to use a direct char *
diff --git a/sc2/src/sc2code/libs/input/sdl/vcontrol.c b/sc2/src/sc2code/libs/input/sdl/vcontrol.c
index d650605b2..68e8f443f 100644
--- a/sc2/src/sc2code/libs/input/sdl/vcontrol.c
+++ b/sc2/src/sc2code/libs/input/sdl/vcontrol.c
@@ -1,11 +1,11 @@
-#include <SDL.h>
+#include "port.h"
+#include SDL_INCLUDE(SDL.h)
 #include <stdlib.h>
 #include <string.h>
 #include <ctype.h>
 #include "vcontrol.h"
 #include "vcontrol_malloc.h"
 #include "keynames.h"
-#include "port.h"
 
 /* How many binding slots are allocated at once. */
 #define POOL_CHUNK_SIZE 64
diff --git a/sc2/src/sc2code/libs/input/sdl/vcontrol.h b/sc2/src/sc2code/libs/input/sdl/vcontrol.h
index 07a8bd0f3..11f831484 100644
--- a/sc2/src/sc2code/libs/input/sdl/vcontrol.h
+++ b/sc2/src/sc2code/libs/input/sdl/vcontrol.h
@@ -1,10 +1,9 @@
-#include <SDL.h>
-
 #ifndef _VCONTROL_H_
 #define _VCONTROL_H_
 
 #include "port.h"
 #include "libs/uio.h"
+#include SDL_INCLUDE(SDL.h)
 
 /* Initialization routines */
 void VControl_Init (void);
diff --git a/sc2/src/sc2code/libs/sound/mixer/sdl/audiodrv_sdl.h b/sc2/src/sc2code/libs/sound/mixer/sdl/audiodrv_sdl.h
index 2a7e3c341..a9cb490f4 100644
--- a/sc2/src/sc2code/libs/sound/mixer/sdl/audiodrv_sdl.h
+++ b/sc2/src/sc2code/libs/sound/mixer/sdl/audiodrv_sdl.h
@@ -20,10 +20,10 @@
 #ifndef _AUDIODRV_SDL_H
 #define _AUDIODRV_SDL_H
 
-#include "config.h"
+#include "port.h"
 #include "libs/sound/sound.h"
 #include "libs/sound/mixer/mixer.h"
-#include <SDL.h>
+#include SDL_INCLUDE(SDL.h)
 
 /* General */
 sint32 mixSDL_Init (audio_Driver *driver, sint32 flags);
diff --git a/sc2/src/sc2code/libs/threads/sdl/sdlthreads.h b/sc2/src/sc2code/libs/threads/sdl/sdlthreads.h
index 19b17a805..76887ad9c 100644
--- a/sc2/src/sc2code/libs/threads/sdl/sdlthreads.h
+++ b/sc2/src/sc2code/libs/threads/sdl/sdlthreads.h
@@ -20,8 +20,9 @@
 #ifndef _SDLTHREAD_H
 #define _SDLTHREAD_H
 
-#include "SDL.h"
-#include "SDL_thread.h"
+#include "port.h"
+#include SDL_INCLUDE(SDL.h)
+#include SDL_INCLUDE(SDL_thread.h)
 #include "libs/threadlib.h"
 #include "libs/timelib.h"
 
diff --git a/sc2/src/sc2code/libs/time/sdl/sdltime.h b/sc2/src/sc2code/libs/time/sdl/sdltime.h
index b73e5cf5b..2e498aabe 100644
--- a/sc2/src/sc2code/libs/time/sdl/sdltime.h
+++ b/sc2/src/sc2code/libs/time/sdl/sdltime.h
@@ -20,7 +20,8 @@
 #ifndef _SDLTIME_H
 #define _SDLTIME_H
 
-#include "SDL.h"
+#include "port.h"
+#include SDL_INCLUDE(SDL.h)
 #include "../timecommon.h"
 
 #define NativeInitTimeSystem()
diff --git a/sc2/src/starcon2.c b/sc2/src/starcon2.c
index ad0c4d157..9d35f5ccf 100644
--- a/sc2/src/starcon2.c
+++ b/sc2/src/starcon2.c
@@ -43,7 +43,7 @@
 
 
 #if defined(GFXMODULE_SDL)
-#	include <SDL.h>
+#	include SDL_INCLUDE(SDL.h)
 			// Including this is actually necessary on OSX.
 #endif