diff --git a/src/xz/coder.c b/src/xz/coder.c
index 69b1225d..f5d372aa 100644
--- a/src/xz/coder.c
+++ b/src/xz/coder.c
@@ -37,10 +37,10 @@ static io_buf in_buf;
 static io_buf out_buf;
 
 /// Number of filters. Zero indicates that we are using a preset.
-static size_t filters_count = 0;
+static uint32_t filters_count = 0;
 
 /// Number of the preset (0-9)
-static size_t preset_number = 6;
+static uint32_t preset_number = 6;
 
 /// If a preset is used (no custom filter chain) and preset_extreme is true,
 /// a significantly slower compression is used to achieve slightly better
@@ -64,7 +64,7 @@ coder_set_check(lzma_check new_check)
 
 
 extern void
-coder_set_preset(size_t new_preset)
+coder_set_preset(uint32_t new_preset)
 {
 	preset_number = new_preset;
 
diff --git a/src/xz/coder.h b/src/xz/coder.h
index 4626466f..2d3add97 100644
--- a/src/xz/coder.h
+++ b/src/xz/coder.h
@@ -46,7 +46,7 @@ extern bool opt_auto_adjust;
 extern void coder_set_check(lzma_check check);
 
 /// Set preset number
-extern void coder_set_preset(size_t new_preset);
+extern void coder_set_preset(uint32_t new_preset);
 
 /// Enable extreme mode
 extern void coder_set_extreme(void);