diff --git a/generator.cpp b/generator.cpp
index 2f0b27a..5dcb048 100644
--- a/generator.cpp
+++ b/generator.cpp
@@ -52,7 +52,7 @@ auto Generator::do_crypto(int64_t k, unsigned __int128 ctr) -> string {
 	return "";
 }
 
-auto Generator::generate_blocks(int k_blocks) -> string {
+auto Generator::generate_blocks(unsigned int k_blocks) -> string {
 	G_state G = get_state();
 	assert (G.ctr!=0);
 	string r = "";
diff --git a/generator.h b/generator.h
index b80e7de..d443ee4 100644
--- a/generator.h
+++ b/generator.h
@@ -11,7 +11,7 @@ using namespace std;
 class Generator {
 public:
 	void initialize_generator();
-	auto generate_blocks(int k_blocks) -> string;
+	auto generate_blocks(unsigned int k_blocks) -> string;
 
 private:
 	struct G_state;