diff --git a/baseconv.c b/baseconv.c
index 4d66799..f566522 100644
--- a/baseconv.c
+++ b/baseconv.c
@@ -7,7 +7,7 @@
 
 static bool baseconv_internal(
 	char outbuf[], size_t bufsize,
-	const char *digits, unsigned base,
+	const char *digits, size_t base,
 	uintmax_t num
 ) {
 	// Supported bases are 2 to number of digits inclusive
@@ -48,7 +48,7 @@ static bool baseconv_internal(
 	return true;
 }
 
-bool baseconv(char outbuf[], size_t bufsize, unsigned base, uintmax_t num) {
+bool baseconv(char outbuf[], size_t bufsize, size_t base, uintmax_t num) {
 	const char *digits = "0123456789abcdefghijklmnopqrstuvwxyz";
 	return baseconv_internal(outbuf, bufsize, digits, base, num);
 }
diff --git a/baseconv.h b/baseconv.h
index 4c4bafa..c7a8cf1 100644
--- a/baseconv.h
+++ b/baseconv.h
@@ -1,2 +1,2 @@
-bool baseconv(char outbuf[], size_t bufsize, unsigned base, uintmax_t num);
+bool baseconv(char outbuf[], size_t bufsize, size_t base, uintmax_t num);
 bool baseconv_digits(char outbuf[], size_t bufsize, const char *digits, uintmax_t num);
diff --git a/main.c b/main.c
index 826fbc1..6030ec5 100644
--- a/main.c
+++ b/main.c
@@ -15,9 +15,9 @@ int main(void) {
 		return 1;
 	}
 
-	unsigned base;
+	size_t base;
 	printf("Base? ");
-	if (scanf("%u", &base) != 1) {
+	if (scanf("%zu", &base) != 1) {
 		fprintf(stderr, "Invalid input\n");
 		return 1;
 	}