diff --git a/src/intel/compiler/brw_inst.cpp b/src/intel/compiler/brw_inst.cpp
index ecf29d7b3f1..4925e6fae8b 100644
--- a/src/intel/compiler/brw_inst.cpp
+++ b/src/intel/compiler/brw_inst.cpp
@@ -395,7 +395,7 @@ brw_inst::can_change_types() const
  * it.
  */
 bool
-brw_inst::is_partial_write() const
+brw_inst::is_partial_write(unsigned grf_size) const
 {
    if (this->predicate && !this->predicate_trivial &&
        this->opcode != BRW_OPCODE_SEL)
@@ -404,10 +404,10 @@ brw_inst::is_partial_write() const
    if (!this->dst.is_contiguous())
       return true;
 
-   if (this->dst.offset % REG_SIZE != 0)
+   if (this->dst.offset % grf_size != 0)
       return true;
 
-   return this->size_written % REG_SIZE != 0;
+   return this->size_written % grf_size != 0;
 }
 
 unsigned
@@ -1239,4 +1239,3 @@ is_coalescing_payload(const brw_shader &s, const brw_inst *inst)
           inst->src[0].offset == 0 &&
           s.alloc.sizes[inst->src[0].nr] * REG_SIZE == inst->size_written;
 }
-
diff --git a/src/intel/compiler/brw_inst.h b/src/intel/compiler/brw_inst.h
index e983d8265eb..84dd35b008d 100644
--- a/src/intel/compiler/brw_inst.h
+++ b/src/intel/compiler/brw_inst.h
@@ -66,7 +66,7 @@ public:
 
    bool is_send_from_grf() const;
    bool is_payload(unsigned arg) const;
-   bool is_partial_write() const;
+   bool is_partial_write(unsigned grf_size = REG_SIZE) const;
    unsigned components_read(unsigned i) const;
    unsigned size_read(const struct intel_device_info *devinfo, int arg) const;
    bool can_do_source_mods(const struct intel_device_info *devinfo) const;
diff --git a/src/intel/compiler/brw_reg_allocate.cpp b/src/intel/compiler/brw_reg_allocate.cpp
index 7673b5219cf..a4d127bf2a7 100644
--- a/src/intel/compiler/brw_reg_allocate.cpp
+++ b/src/intel/compiler/brw_reg_allocate.cpp
@@ -1227,7 +1227,7 @@ brw_reg_alloc::spill_reg(unsigned spill_reg)
           * write, there should be no need for the unspill since the
           * instruction will be overwriting the whole destination in any case.
 	  */
-         if (inst->is_partial_write() ||
+         if (inst->is_partial_write(reg_unit(devinfo) * REG_SIZE) ||
              (!inst->force_writemask_all && !per_channel))
             emit_unspill(ubld, &fs->shader_stats, spill_src,
                          subset_spill_offset, regs_written(inst), ip);