diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index 507f2ee73cf..f73d6782528 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -587,15 +587,18 @@ type_size_vec4(const struct glsl_type *type)
    case GLSL_TYPE_INT:
    case GLSL_TYPE_FLOAT:
    case GLSL_TYPE_BOOL:
+   case GLSL_TYPE_DOUBLE:
       if (type->is_matrix()) {
-	 return type->matrix_columns;
+         const glsl_type *col_type = type->column_type();
+         unsigned col_slots = col_type->is_dual_slot_double() ? 2 : 1;
+         return type->matrix_columns * col_slots;
       } else {
-	 /* Regardless of size of vector, it gets a vec4. This is bad
-	  * packing for things like floats, but otherwise arrays become a
-	  * mess.  Hopefully a later pass over the code can pack scalars
-	  * down if appropriate.
-	  */
-	 return 1;
+         /* Regardless of size of vector, it gets a vec4. This is bad
+          * packing for things like floats, but otherwise arrays become a
+          * mess.  Hopefully a later pass over the code can pack scalars
+          * down if appropriate.
+          */
+         return type->is_dual_slot_double() ? 2 : 1;
       }
    case GLSL_TYPE_ARRAY:
       assert(type->length > 0);
@@ -619,7 +622,6 @@ type_size_vec4(const struct glsl_type *type)
    case GLSL_TYPE_IMAGE:
       return DIV_ROUND_UP(BRW_IMAGE_PARAM_SIZE, 4);
    case GLSL_TYPE_VOID:
-   case GLSL_TYPE_DOUBLE:
    case GLSL_TYPE_ERROR:
    case GLSL_TYPE_INTERFACE:
    case GLSL_TYPE_FUNCTION: