diff --git a/checkin_notes b/checkin_notes
index e3f286dc83..7c774d89b5 100644
--- a/checkin_notes
+++ b/checkin_notes
@@ -202,3 +202,10 @@ David  5 Jan 2012
 
     lib/
         gui_rpc_client_ops.cpp
+
+Rom    3 Jan 2012
+    - client: Restore scaling factor for AMD OpenCL devices on Macs with 
+        OpenCL version < 1.2.
+    
+    client/
+        coproc_detect.cpp
diff --git a/client/coproc_detect.cpp b/client/coproc_detect.cpp
index 34e867192a..1989a79d8f 100644
--- a/client/coproc_detect.cpp
+++ b/client/coproc_detect.cpp
@@ -293,6 +293,21 @@ void COPROCS::get_opencl(
                 (strstr(prop.vendor, "Advanced Micro Devices, Inc."))
             ) {
                 prop.device_num = (int)(ati_opencls.size());
+#ifdef __APPLE__
+                // Work around a bug in OpenCL which returns only 
+                // 1/2 of total global RAM size. 
+                // This bug applies only to ATI GPUs, not to NVIDIA
+                // This has already been fixed on latest Catalyst 
+                // drivers, but Mac does not use Catalyst drivers.
+                // Assume this will be fixed in openCL 1.2.
+                // See also further workaround code for systems with 
+                // CAL support.
+                if ((!strstr("1.0", prop.opencl_platform_version))
+                    || (!strstr("1.1", prop.opencl_platform_version))
+                ){
+                    prop.global_mem_size *= 2;
+                }
+#endif
                 if (!ati.have_cal) {
                     COPROC_ATI c;
                     c.opencl_prop = prop;
@@ -329,6 +344,7 @@ void COPROCS::get_opencl(
         // Work around a bug in OpenCL which returns only 
         // 1/2 of total global RAM size: use the value from CAL. 
         // This bug applies only to ATI GPUs, not to NVIDIA
+        // See also further workaround code for Macs.
         //
         ati.opencl_prop.global_mem_size = ati.attribs.localRAM * MEGA;
     } else {