diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7de1a0a9..2ba81a80 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -245,6 +245,7 @@ check_include_file(sys/time.h HAVE_SYS_TIME_H)
 check_include_file(sys/timeb.h HAVE_SYS_TIMEB_H)
 check_include_file(unistd.h HAVE_UNISTD_H)
 check_include_file(windows.h HAVE_WINDOWS_H)
+check_include_file(AL/alext.h HAVE_AL_EXT_H)
 
 if(HAVE_INTTYPES_H)
   # ShivaVG needs inttypes.h
diff --git a/simgear/simgear_config_cmake.h.in b/simgear/simgear_config_cmake.h.in
index 0cce4b31..c9804e7c 100644
--- a/simgear/simgear_config_cmake.h.in
+++ b/simgear/simgear_config_cmake.h.in
@@ -13,6 +13,8 @@
 #cmakedefine HAVE_STD_ISNAN
 #cmakedefine HAVE_WINDOWS_H
 #cmakedefine HAVE_MKDTEMP
+#cmakedefine HAVE_AL_EXT_H
+
 
 #cmakedefine GCC_ATOMIC_BUILTINS_FOUND
 
diff --git a/simgear/sound/soundmgr_openal.cxx b/simgear/sound/soundmgr_openal.cxx
index 68147b0b..1dfbafa7 100644
--- a/simgear/sound/soundmgr_openal.cxx
+++ b/simgear/sound/soundmgr_openal.cxx
@@ -762,7 +762,7 @@ bool SGSoundMgr::load( const std::string &samplepath,
     if ( !is_working() )
         return false;
 
-    ALenum format;
+    unsigned int format;
     ALsizei size;
     ALsizei freq;
     ALvoid *data;
diff --git a/simgear/sound/soundmgr_openal_private.hxx b/simgear/sound/soundmgr_openal_private.hxx
index 6bc3591f..d1b4f85a 100644
--- a/simgear/sound/soundmgr_openal_private.hxx
+++ b/simgear/sound/soundmgr_openal_private.hxx
@@ -29,6 +29,10 @@
 #ifndef _SG_SOUNDMGR_OPENAL_PRIVATE_HXX
 #define _SG_SOUNDMGR_OPENAL_PRIVATE_HXX 1
 
+#ifdef HAVE_CONFIG_H
+#  include <simgear_config.h>
+#endif
+
 #include <string>
 #include <vector>
 #include <map>
@@ -36,15 +40,15 @@
 #if defined(__APPLE__)
 # include <OpenAL/al.h>
 # include <OpenAL/alc.h>
-# include <OpenAL/alext.h>
 #elif defined(OPENALSDK)
 # include <al.h>
 # include <alc.h>
-# include <alext.h>
 #else
 # include <AL/al.h>
 # include <AL/alc.h>
-# include <AL/alext.h>
+# ifdef HAVE_AL_EXT_H
+#  include <AL/alext.h>
+# endif
 #endif
 
 #include <simgear/structure/SGSharedPtr.hxx>