diff --git a/lib/isc/hash.c b/lib/isc/hash.c
index 1a28a216a7..2783a37e41 100644
--- a/lib/isc/hash.c
+++ b/lib/isc/hash.c
@@ -18,7 +18,6 @@
 #include <isc/ascii.h>
 #include <isc/entropy.h>
 #include <isc/hash.h> /* IWYU pragma: keep */
-#include <isc/once.h>
 #include <isc/random.h>
 #include <isc/result.h>
 #include <isc/siphash.h>
@@ -27,34 +26,24 @@
 #include <isc/util.h>
 
 static uint8_t isc_hash_key[16];
-static uint8_t isc_hash32_key[8];
-static bool hash_initialized = false;
-static isc_once_t isc_hash_once = ISC_ONCE_INIT;
 
-static void
-isc_hash_initialize(void) {
+void
+isc__hash_initialize(void) {
 	/*
 	 * Set a constant key to help in problem reproduction should
 	 * fuzzing find a crash or a hang.
 	 */
-	uint64_t key[2] = { 0, 1 };
+	uint8_t key[16] = { 1 };
 #if !FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
 	isc_entropy_get(key, sizeof(key));
 #endif /* if FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */
+	STATIC_ASSERT(sizeof(key) >= sizeof(isc_hash_key),
+		      "sizeof(key) < sizeof(isc_hash_key)");
 	memmove(isc_hash_key, key, sizeof(isc_hash_key));
-#if !FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
-	isc_entropy_get(key, sizeof(key));
-#endif /* if FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION */
-	memmove(isc_hash32_key, key, sizeof(isc_hash32_key));
-	hash_initialized = true;
 }
 
 const void *
 isc_hash_get_initializer(void) {
-	if (!hash_initialized) {
-		isc_once_do(&isc_hash_once, isc_hash_initialize);
-	}
-
 	return (isc_hash_key);
 }
 
@@ -62,41 +51,49 @@ void
 isc_hash_set_initializer(const void *initializer) {
 	REQUIRE(initializer != NULL);
 
-	/*
-	 * Ensure that isc_hash_initialize() is not called after
-	 * isc_hash_set_initializer() is called.
-	 */
-	if (!hash_initialized) {
-		isc_once_do(&isc_hash_once, isc_hash_initialize);
-	}
-
 	memmove(isc_hash_key, initializer, sizeof(isc_hash_key));
 }
 
-uint64_t
-isc_hash64(const void *data, const size_t length, const bool case_sensitive) {
-	uint64_t hval;
+void
+isc_hash32_init(isc_hash32_t *restrict state) {
+	isc_halfsiphash24_init(state, isc_hash_key);
+}
 
+void
+isc_hash32_hash(isc_hash32_t *restrict state, const void *data,
+		const size_t length, const bool case_sensitive) {
 	REQUIRE(length == 0 || data != NULL);
 
-	isc_once_do(&isc_hash_once, isc_hash_initialize);
-
-	isc_siphash24(isc_hash_key, data, length, case_sensitive,
-		      (uint8_t *)&hval);
-
-	return (hval);
+	isc_halfsiphash24_hash(state, data, length, case_sensitive);
 }
 
 uint32_t
-isc_hash32(const void *data, const size_t length, const bool case_sensitive) {
+isc_hash32_finalize(isc_hash32_t *restrict state) {
 	uint32_t hval;
 
-	REQUIRE(length == 0 || data != NULL);
-
-	isc_once_do(&isc_hash_once, isc_hash_initialize);
-
-	isc_halfsiphash24(isc_hash_key, data, length, case_sensitive,
-			  (uint8_t *)&hval);
+	isc_halfsiphash24_finalize(state, (uint8_t *)&hval);
+
+	return (hval);
+}
+
+void
+isc_hash64_init(isc_hash64_t *restrict state) {
+	isc_siphash24_init(state, isc_hash_key);
+}
+
+void
+isc_hash64_hash(isc_hash64_t *restrict state, const void *data,
+		const size_t length, const bool case_sensitive) {
+	REQUIRE(length == 0 || data != NULL);
+
+	isc_siphash24_hash(state, data, length, case_sensitive);
+}
+
+uint64_t
+isc_hash64_finalize(isc_hash64_t *restrict state) {
+	uint64_t hval;
+
+	isc_siphash24_finalize(state, (uint8_t *)&hval);
 
 	return (hval);
 }
diff --git a/lib/isc/include/isc/hash.h b/lib/isc/include/isc/hash.h
index c3926157d0..bac9d9f7b8 100644
--- a/lib/isc/include/isc/hash.h
+++ b/lib/isc/include/isc/hash.h
@@ -18,6 +18,7 @@
 
 #include <isc/assertions.h>
 #include <isc/lang.h>
+#include <isc/siphash.h>
 #include <isc/types.h>
 #include <isc/util.h>
 
@@ -26,11 +27,17 @@
 #define ISC_HASH_MIN_BITS   2U
 #define ISC_HASH_MAX_BITS   32U
 
+typedef struct isc_halfsiphash24 isc_hash32_t;
+typedef struct isc_siphash24	 isc_hash64_t;
+
 /***
  *** Functions
  ***/
 ISC_LANG_BEGINDECLS
 
+void
+isc__hash_initialize(void);
+
 const void *
 isc_hash_get_initializer(void);
 
@@ -39,10 +46,35 @@ isc_hash_set_initializer(const void *initializer);
 
 #define isc_hash_function isc_hash64
 
+void
+isc_hash32_init(isc_hash32_t *restrict state);
+void
+isc_hash32_hash(isc_hash32_t *restrict state, const void *data,
+		const size_t length, const bool case_sensitive);
 uint32_t
-isc_hash32(const void *data, const size_t length, const bool case_sensitive);
+isc_hash32_finalize(isc_hash32_t *restrict state);
+static inline uint32_t
+isc_hash32(const void *data, const size_t length, const bool case_sensitive) {
+	isc_hash32_t state;
+	isc_hash32_init(&state);
+	isc_hash32_hash(&state, data, length, case_sensitive);
+	return (isc_hash32_finalize(&state));
+}
+
+void
+isc_hash64_init(isc_hash64_t *restrict state);
+void
+isc_hash64_hash(isc_hash64_t *restrict state, const void *data,
+		const size_t length, const bool case_sensitive);
 uint64_t
-isc_hash64(const void *data, const size_t length, const bool case_sensitive);
+isc_hash64_finalize(isc_hash64_t *restrict state);
+static inline uint64_t
+isc_hash64(const void *data, const size_t length, const bool case_sensitive) {
+	isc_hash64_t state;
+	isc_hash64_init(&state);
+	isc_hash64_hash(&state, data, length, case_sensitive);
+	return (isc_hash64_finalize(&state));
+}
 /*!<
  * \brief Calculate a hash over data.
  *
diff --git a/lib/isc/lib.c b/lib/isc/lib.c
index aba5dc1db8..4fd65e6020 100644
--- a/lib/isc/lib.c
+++ b/lib/isc/lib.c
@@ -13,6 +13,7 @@
 
 /*! \file */
 
+#include <isc/hash.h>
 #include <isc/iterated_hash.h>
 #include <isc/md.h>
 #include <isc/mem.h>
@@ -50,6 +51,7 @@ isc__initialize(void) {
 	isc__uv_initialize();
 	isc__xml_initialize();
 	isc__md_initialize();
+	isc__hash_initialize();
 	isc__iterated_hash_initialize();
 	(void)isc_os_ncpus();
 	rcu_register_thread();