diff --git a/build/mac/build_scripts/Moz/BuildFlags.pm b/build/mac/build_scripts/Moz/BuildFlags.pm
index 7091f98a1d5e..46760e8f3f3a 100644
--- a/build/mac/build_scripts/Moz/BuildFlags.pm
+++ b/build/mac/build_scripts/Moz/BuildFlags.pm
@@ -220,6 +220,7 @@ sub SetOptionDefines($)
   $optiondefines->{"svg"}{"MOZ_SVG"}          = 1;
   $optiondefines->{"carbon"}{"TARGET_CARBON"} = 1;
   $optiondefines->{"cache"}{"MOZ_NEW_CACHE"}  = 1;
+  $optiondefines->{"soap"}{"MOZ_SOAP"}        = 1;
 }
 
 
diff --git a/build/mac/build_scripts/MozillaBuildFlags.txt b/build/mac/build_scripts/MozillaBuildFlags.txt
index 5f0c365059fd..f2eccaaf350c 100644
--- a/build/mac/build_scripts/MozillaBuildFlags.txt
+++ b/build/mac/build_scripts/MozillaBuildFlags.txt
@@ -41,7 +41,8 @@ mathml          0
 svg             0
 mng             1
 ldap            0
-xmlextras       0
+xmlextras       1
+soap            0
 mailextras      1
 xptlink         0
 psm             0
diff --git a/build/mac/build_scripts/MozillaBuildList.pm b/build/mac/build_scripts/MozillaBuildList.pm
index 94e3ebafcc8e..42b0a3a21396 100644
--- a/build/mac/build_scripts/MozillaBuildList.pm
+++ b/build/mac/build_scripts/MozillaBuildList.pm
@@ -784,6 +784,9 @@ sub BuildClientDist()
     if ($main::options{xmlextras})
     {
         InstallFromManifest(":mozilla:extensions:xmlextras:base:public:MANIFEST_IDL", "$distdirectory:idl:");
+    }
+    if ($main::options{soap})
+    {
         InstallFromManifest(":mozilla:extensions:xmlextras:soap:public:MANIFEST_IDL", "$distdirectory:idl:");
     }
 
@@ -1029,6 +1032,10 @@ sub BuildIDLProjects()
     {
         BuildIDLProject(":mozilla:extensions:xmlextras:macbuild:xmlextrasIDL.mcp", "xmlextras");
     }
+    if ($main::options{soap})
+    {
+        BuildIDLProject(":mozilla:extensions:xmlextras:macbuild:xmlsoapIDL.mcp", "xmlsoap");
+    }
 
     EndBuildModule("idl");
 }
@@ -1556,6 +1563,14 @@ sub BuildExtensionsProjects()
     }
     
     # XML Extras
+    if ($main::options{soap})
+    {
+        BuildOneProject(":mozilla:extensions:xmlextras:macbuild:xmlsoap.mcp", "xmlsoap$D.o", 0, 0, 0);
+    }
+    else
+    {
+        BuildOneProject(":mozilla:extensions:xmlextras:macbuild:xmlsoap.mcp", "xmlsoap$D.o stub", 0, 0, 0);
+    }
     if ($main::options{xmlextras})
     {
         BuildOneProject(":mozilla:extensions:xmlextras:macbuild:xmlextras.mcp", "xmlextras$D.shlb", 1, $main::ALIAS_SYM_FILES, 1);