diff --git a/src/cairo-lzw.c b/src/cairo-lzw.c
index bb764f3a8..a0d737e25 100644
--- a/src/cairo-lzw.c
+++ b/src/cairo-lzw.c
@@ -460,14 +460,14 @@ cl_hash (LZWCodecState* sp)
  */
 
 void *
-_cairo_compress_lzw (void *data, unsigned long data_size, unsigned long *compressed_size)
+_cairo_lzw_compress (void *data, unsigned long *data_size_in_out)
 {
     LZWCodecState state;
     
     if (!LZWSetupEncode (&state))
 	goto bail0;
     
-    state.out_buffer_size = data_size/4;
+    state.out_buffer_size = *data_size_in_out/4;
     /* We need *some* space at least */
     if (state.out_buffer_size < 256)
 	state.out_buffer_size = 256;
@@ -479,14 +479,14 @@ _cairo_compress_lzw (void *data, unsigned long data_size, unsigned long *compres
     state.out_buffer_bytes = 0;
     
     LZWPreEncode (&state);
-    if (!LZWEncode (&state, data, data_size))
+    if (!LZWEncode (&state, data, *data_size_in_out))
 	goto bail2;
     if (!LZWPostEncode(&state))
 	goto bail2;
     
     LZWFreeEncode(&state);
 
-    *compressed_size = state.out_buffer_bytes;
+    *data_size_in_out = state.out_buffer_bytes;
     return state.out_buffer;
     
  bail2:
diff --git a/src/cairo-ps-surface.c b/src/cairo-ps-surface.c
index ff4f0e8c4..a646d45ba 100644
--- a/src/cairo-ps-surface.c
+++ b/src/cairo-ps-surface.c
@@ -724,7 +724,8 @@ emit_image (cairo_ps_surface_t    *surface,
 	}
     }
 
-    compressed = _cairo_compress_lzw (rgb, rgb_size, &compressed_size);
+    compressed_size = rgb_size;
+    compressed = _cairo_lzw_compress (rgb, &compressed_size);
     if (compressed == NULL) {
 	status = CAIRO_STATUS_NO_MEMORY;
 	goto bail2;
diff --git a/src/cairoint.h b/src/cairoint.h
index d5abfc79a..fdb8fc5df 100644
--- a/src/cairoint.h
+++ b/src/cairoint.h
@@ -2146,9 +2146,7 @@ _cairo_output_stream_write_base85_string (cairo_output_stream_t *stream,
 					  size_t length);
 
 cairo_private void *
-_cairo_compress_lzw (void *data,
-		     unsigned long data_size,
-		     unsigned long *compressed_size);
+_cairo_lzw_compress (void *data, unsigned long *data_size_in_out);
 
 cairo_private cairo_status_t
 _cairo_output_stream_vprintf (cairo_output_stream_t *stream,