diff --git a/src/common/classes/Hash.cpp b/src/common/classes/Hash.cpp
index afe31c9a84..605088fa06 100644
--- a/src/common/classes/Hash.cpp
+++ b/src/common/classes/Hash.cpp
@@ -108,3 +108,26 @@ unsigned int InternalHash::hash(unsigned int length, const UCHAR* value)
 {
 	return internalHash(length, value);
 }
+
+
+void WeakHashContext::update(const void* data, FB_SIZE_T length)
+{
+	const UCHAR* p = static_cast<const UCHAR*>(data);
+
+	for (const UCHAR* end = p + length; p != end; ++p)
+	{
+		hashNumber = (hashNumber << 4) + *p;
+
+		const SINT64 n = hashNumber & FB_CONST64(0xF000000000000000);
+		if (n)
+			hashNumber ^= n >> 56;
+
+		hashNumber &= ~n;
+	}
+}
+
+void WeakHashContext::finish(Buffer& result)
+{
+	UCHAR* resultBuffer = result.getBuffer(sizeof(hashNumber));
+	memcpy(resultBuffer, &hashNumber, sizeof(hashNumber));
+}
diff --git a/src/common/classes/Hash.h b/src/common/classes/Hash.h
index 39aaa5b46f..b0ee25052f 100644
--- a/src/common/classes/Hash.h
+++ b/src/common/classes/Hash.h
@@ -28,7 +28,7 @@
 #ifndef CLASSES_HASH_H
 #define CLASSES_HASH_H
 
-#include "../common/classes/vector.h"
+#include "../common/classes/array.h"
 
 namespace Firebird
 {
@@ -341,7 +341,31 @@ namespace Firebird
 		}
 	};
 
+
+	class HashContext
+	{
+	public:
+		typedef HalfStaticArray<UCHAR, 256> Buffer;
+
+	public:
+		virtual ~HashContext()
+		{
+		}
+
+	public:
+		virtual void update(const void* data, FB_SIZE_T length) = 0;
+		virtual void finish(Buffer& result) = 0;
+	};
+
+	class WeakHashContext FB_FINAL : public HashContext
+	{
+	public:
+		virtual void update(const void* data, FB_SIZE_T length);
+		virtual void finish(Buffer& result);
+
+	private:
+		SINT64 hashNumber = 0;
+	};
 } // namespace Firebird
 
 #endif // CLASSES_HASH_H
-
diff --git a/src/jrd/SysFunction.cpp b/src/jrd/SysFunction.cpp
index a72f23bf66..16e6ded39e 100644
--- a/src/jrd/SysFunction.cpp
+++ b/src/jrd/SysFunction.cpp
@@ -30,6 +30,7 @@
 
 #include "firebird.h"
 #include "../common/classes/VaryStr.h"
+#include "../common/classes/Hash.h"
 #include "../jrd/SysFunction.h"
 #include "../jrd/DataTypeUtil.h"
 #include "../include/fb_blk.h"
@@ -2647,10 +2648,9 @@ dsc* evlHash(thread_db* tdbb, const SysFunction*, const NestValueArray& args,
 	if (request->req_flags & req_null)	// return NULL if value is NULL
 		return NULL;
 
+	WeakHashContext hashContext;
 	impure->vlu_misc.vlu_int64 = 0;
 
-	UCHAR* address;
-
 	if (value->isBlob())
 	{
 		UCHAR buffer[BUFFER_LARGE];
@@ -2659,38 +2659,26 @@ dsc* evlHash(thread_db* tdbb, const SysFunction*, const NestValueArray& args,
 
 		while (!(blob->blb_flags & BLB_eof))
 		{
-			address = buffer;
-			const ULONG length = blob->BLB_get_data(tdbb, address, sizeof(buffer), false);
-
-			for (const UCHAR* end = address + length; address < end; ++address)
-			{
-				impure->vlu_misc.vlu_int64 = (impure->vlu_misc.vlu_int64 << 4) + *address;
-
-				const SINT64 n = impure->vlu_misc.vlu_int64 & FB_CONST64(0xF000000000000000);
-				if (n)
-					impure->vlu_misc.vlu_int64 ^= n >> 56;
-				impure->vlu_misc.vlu_int64 &= ~n;
-			}
+			const ULONG length = blob->BLB_get_data(tdbb, buffer, sizeof(buffer), false);
+			hashContext.update(buffer, length);
 		}
 
 		blob->BLB_close(tdbb);
 	}
 	else
 	{
+		UCHAR* address;
 		MoveBuffer buffer;
 		const ULONG length = MOV_make_string2(tdbb, value, value->getTextType(), &address, buffer, false);
-
-		for (const UCHAR* end = address + length; address < end; ++address)
-		{
-			impure->vlu_misc.vlu_int64 = (impure->vlu_misc.vlu_int64 << 4) + *address;
-
-			const SINT64 n = impure->vlu_misc.vlu_int64 & FB_CONST64(0xF000000000000000);
-			if (n)
-				impure->vlu_misc.vlu_int64 ^= n >> 56;
-			impure->vlu_misc.vlu_int64 &= ~n;
-		}
+		hashContext.update(address, length);
 	}
 
+	HashContext::Buffer resultBuffer;
+	hashContext.finish(resultBuffer);
+
+	fb_assert(resultBuffer.getCount() == sizeof(SINT64));
+	memcpy(&impure->vlu_misc.vlu_int64, resultBuffer.begin(), sizeof(SINT64));
+
 	// make descriptor for return value
 	impure->vlu_desc.makeInt64(0, &impure->vlu_misc.vlu_int64);