diff --git a/m4/ax_mexopts.m4 b/m4/ax_mexopts.m4
index 89200e6a737cf107c8c46a20b3eb0f1ad3c2094e..6f02fef50ffce7d68741f7395791b5cbfc40fe82 100644
--- a/m4/ax_mexopts.m4
+++ b/m4/ax_mexopts.m4
@@ -62,8 +62,8 @@ case ${MATLAB_ARCH} in
     ax_mexopts_ok="yes"
     ;;
   maci | maci64)
-    SDKROOT='/Developer/SDKs/MacOSX10.5.sdk'
-    MACOSX_DEPLOYMENT_TARGET='10.5'
+    SDKROOT='/Developer/SDKs/MacOSX10.6.sdk'
+    MACOSX_DEPLOYMENT_TARGET='10.6'
     if test "${MATLAB_ARCH}" = "maci"; then
         ARCHS='i386'
         MATLAB_FFLAGS=''