diff --git a/block.c b/block.c
index 6a870be..ad58ad9 100644
--- a/block.c
+++ b/block.c
@@ -30,7 +30,7 @@ void pixz_block_free(pixz_block *b) {
     free(b);
 }
 
-int pixz_block_full(pixz_block *b) {
+bool pixz_block_full(pixz_block *b) {
     return pixz_block_new_input_avail(b) == 0;
 }
 
diff --git a/pixz.h b/pixz.h
index 7a1947a..6ea97e8 100644
--- a/pixz.h
+++ b/pixz.h
@@ -24,7 +24,7 @@ typedef struct {
 pixz_block *pixz_block_new(size_t size, lzma_check check, lzma_filter *filters);
 void pixz_block_free(pixz_block *b);
 
-int pixz_block_full(pixz_block *b);
+bool pixz_block_full(pixz_block *b);
 size_t pixz_block_new_input_avail(pixz_block *b);
 uint8_t *pixz_block_new_input_next(pixz_block *b);
 void pixz_block_new_input(pixz_block *b, size_t bytes);