diff --git a/src/basic/random-util.c b/src/basic/random-util.c
index eca8187571..a125e5228e 100644
--- a/src/basic/random-util.c
+++ b/src/basic/random-util.c
@@ -495,7 +495,7 @@ int random_write_entropy(int fd, const void *seed, size_t size, bool credit) {
         return 1;
 }
 
-int random_u64_range(uint64_t m) {
+uint64_t random_u64_range(uint64_t m) {
         uint64_t x, remainder;
 
         /* Generates a random number in the range 0…m-1, unbiased. (Java's algorithm) */
diff --git a/src/basic/random-util.h b/src/basic/random-util.h
index 1d5fb60fa2..e6528ddc7f 100644
--- a/src/basic/random-util.h
+++ b/src/basic/random-util.h
@@ -41,4 +41,4 @@ size_t random_pool_size(void);
 
 int random_write_entropy(int fd, const void *seed, size_t size, bool credit);
 
-int random_u64_range(uint64_t max);
+uint64_t random_u64_range(uint64_t max);