diff --git a/kernel/driver.cc b/kernel/driver.cc
index 2923bf5fd..cbbf7ce68 100644
--- a/kernel/driver.cc
+++ b/kernel/driver.cc
@@ -271,7 +271,7 @@ int main(int argc, char **argv)
 		("X,trace", "enable tracing of core data structure changes. for debugging")
 		("M,randomize-pointers", "will slightly randomize allocated pointer addresses. for debugging")
 		("hash-seed", "mix up hashing values with <seed>, for extreme optimization and testing",
-			cxxopts::value<int>(), "<seed>")
+			cxxopts::value<uint64_t>(), "<seed>")
 		("A,abort", "will call abort() at the end of the script. for debugging")
 		("x,experimental", "do not print warnings for the experimental <feature>",
 			cxxopts::value<std::vector<std::string>>(), "<feature>")
@@ -419,8 +419,8 @@ int main(int argc, char **argv)
 			frontend_files = result["infile"].as<std::vector<std::string>>();
 		}
 		if (result.count("hash-seed")) {
-			int seed = result["hash-seed"].as<int>();
-			Hasher::set_fudge(seed);
+			int seed = result["hash-seed"].as<uint64_t>();
+			Hasher::set_fudge((Hasher::hash_t)seed);
 		}
 
 		if (log_errfile == NULL) {