diff --git a/src/com/sheepit/client/os/Mac.java b/src/com/sheepit/client/os/Mac.java
index 2993ff0..795557e 100644
--- a/src/com/sheepit/client/os/Mac.java
+++ b/src/com/sheepit/client/os/Mac.java
@@ -71,7 +71,7 @@ public class Mac extends OS {
 	@Override public boolean isSupported() {
 		String[] ver = operatingSystem.getVersionInfo().getVersion().split("\\.");
 		int majorVer = Integer.parseInt(ver[0]), minorVer = Integer.parseInt(ver[1]);
-		return (majorVer == 10 && minorVer >= 13) || majorVer >= 11;
+		return super.isSupported() && ((majorVer == 10 && minorVer >= 13) || majorVer >= 11);
 	}
 	
 	@Override public String getCUDALib() {
diff --git a/src/com/sheepit/client/os/OS.java b/src/com/sheepit/client/os/OS.java
index 650796e..dc4440f 100644
--- a/src/com/sheepit/client/os/OS.java
+++ b/src/com/sheepit/client/os/OS.java
@@ -39,7 +39,7 @@ public abstract class OS {
 	
 	public abstract String name();
 	
-	public boolean isSupported() { return true; }
+	public boolean isSupported() {  return "64bit".equals(getCPU().arch()); }
 	
 	/** Get the full version of the os.
 	 * For example windows, should give "windows 8.1"
diff --git a/src/com/sheepit/client/os/Windows.java b/src/com/sheepit/client/os/Windows.java
index f29ce49..7e13d78 100644
--- a/src/com/sheepit/client/os/Windows.java
+++ b/src/com/sheepit/client/os/Windows.java
@@ -76,7 +76,7 @@ public class Windows extends OS {
 	
 	@Override public boolean isSupported() {
 		String ver = operatingSystem.getVersionInfo().getVersion();
-		return ver.equals("8.1") || ver.equals("10") || ver.equals("11");
+		return super.isSupported() && (ver.equals("8.1") || ver.equals("10") || ver.equals("11"));
 	}
 	
 	int getPriorityClass(int priority) {