diff --git a/lib/deflate_compress.c b/lib/deflate_compress.c
index 604675b..8d9037a 100644
--- a/lib/deflate_compress.c
+++ b/lib/deflate_compress.c
@@ -2646,7 +2646,7 @@ deflate_init_offset_slot_fast(struct libdeflate_compressor *c)
 }
 
 LIBEXPORT struct libdeflate_compressor *
-libdeflate_alloc_compressor(unsigned int compression_level)
+libdeflate_alloc_compressor(int compression_level)
 {
 	struct libdeflate_compressor *c;
 	size_t size;
@@ -2662,8 +2662,6 @@ libdeflate_alloc_compressor(unsigned int compression_level)
 	if (!c)
 		return NULL;
 
-	c->compression_level = compression_level;
-
 	switch (compression_level) {
 	case 1:
 		c->impl = deflate_compress_greedy;
@@ -2748,6 +2746,8 @@ libdeflate_alloc_compressor(unsigned int compression_level)
 		return NULL;
 	}
 
+	c->compression_level = compression_level;
+
 	deflate_init_offset_slot_fast(c);
 	deflate_init_static_codes(c);
 
diff --git a/libdeflate.h b/libdeflate.h
index c7c220b..6eabdac 100644
--- a/libdeflate.h
+++ b/libdeflate.h
@@ -49,7 +49,7 @@ struct libdeflate_compressor;
  * However, different threads may use different compressors concurrently.
  */
 LIBDEFLATEAPI struct libdeflate_compressor *
-libdeflate_alloc_compressor(unsigned int compression_level);
+libdeflate_alloc_compressor(int compression_level);
 
 /*
  * libdeflate_deflate_compress() performs raw DEFLATE compression on a buffer of