diff --git a/src/jrd/SysFunction.cpp b/src/jrd/SysFunction.cpp
index 6a9a94bc71..678b916256 100644
--- a/src/jrd/SysFunction.cpp
+++ b/src/jrd/SysFunction.cpp
@@ -159,22 +159,32 @@ static double cot(double value)
 }
 
 
-static void makeDoubleResult(DataTypeUtilBase* dataTypeUtil, SysFunction* function, dsc* result, int argsCount, const dsc** args)
+static bool initResult(dsc* result, int argsCount, const dsc** args, bool* isNullable)
 {
-	bool isNullable = false;
+	*isNullable = false;
 
 	for (int i = 0; i < argsCount; ++i)
 	{
 		if (args[i]->isNull())
 		{
 			result->makeNullString();
-			return;
+			return true;
 		}
 
 		if (args[i]->isNullable())
-			isNullable = true;
+			*isNullable = true;
 	}
 
+	return false;
+}
+
+
+static void makeDoubleResult(DataTypeUtilBase* dataTypeUtil, SysFunction* function, dsc* result, int argsCount, const dsc** args)
+{
+	bool isNullable;
+	if (initResult(result, argsCount, args, &isNullable))
+		return;
+
 	result->makeDouble();
 	result->setNullable(isNullable);
 }
@@ -189,19 +199,9 @@ static void makeFromListResult(DataTypeUtilBase* dataTypeUtil, SysFunction* func
 
 static void makeInt64Result(DataTypeUtilBase* dataTypeUtil, SysFunction* function, dsc* result, int argsCount, const dsc** args)
 {
-	bool isNullable = false;
-
-	for (int i = 0; i < argsCount; ++i)
-	{
-		if (args[i]->isNull())
-		{
-			result->makeNullString();
-			return;
-		}
-
-		if (args[i]->isNullable())
-			isNullable = true;
-	}
+	bool isNullable;
+	if (initResult(result, argsCount, args, &isNullable))
+		return;
 
 	result->makeInt64(0);
 	result->setNullable(isNullable);
@@ -210,19 +210,9 @@ static void makeInt64Result(DataTypeUtilBase* dataTypeUtil, SysFunction* functio
 
 static void makeLongResult(DataTypeUtilBase* dataTypeUtil, SysFunction* function, dsc* result, int argsCount, const dsc** args)
 {
-	bool isNullable = false;
-
-	for (int i = 0; i < argsCount; ++i)
-	{
-		if (args[i]->isNull())
-		{
-			result->makeNullString();
-			return;
-		}
-
-		if (args[i]->isNullable())
-			isNullable = true;
-	}
+	bool isNullable;
+	if (initResult(result, argsCount, args, &isNullable))
+		return;
 
 	result->makeLong(0);
 	result->setNullable(isNullable);
@@ -244,19 +234,9 @@ static void makeLongStringOrBlobResult(DataTypeUtilBase* dataTypeUtil, SysFuncti
 
 static void makeShortResult(DataTypeUtilBase* dataTypeUtil, SysFunction* function, dsc* result, int argsCount, const dsc** args)
 {
-	bool isNullable = false;
-
-	for (int i = 0; i < argsCount; ++i)
-	{
-		if (args[i]->isNull())
-		{
-			result->makeNullString();
-			return;
-		}
-
-		if (args[i]->isNullable())
-			isNullable = true;
-	}
+	bool isNullable;
+	if (initResult(result, argsCount, args, &isNullable))
+		return;
 
 	result->makeShort(0);
 	result->setNullable(isNullable);
@@ -487,19 +467,9 @@ static void makeOverlay(DataTypeUtilBase* dataTypeUtil, SysFunction* function, d
 {
 	fb_assert(argsCount >= function->minArgCount);
 
-	bool isNullable = false;
-
-	for (int i = 0; i < argsCount; ++i)
-	{
-		if (args[i]->isNull())
-		{
-			result->makeNullString();
-			return;
-		}
-
-		if (args[i]->isNullable())
-			isNullable = true;
-	}
+	bool isNullable;
+	if (initResult(result, argsCount, args, &isNullable))
+		return;
 
 	const dsc* value = args[0];
 	const dsc* placing = args[1];
@@ -532,19 +502,9 @@ static void makePad(DataTypeUtilBase* dataTypeUtil, SysFunction* function, dsc*
 {
 	fb_assert(argsCount >= function->minArgCount);
 
-	bool isNullable = false;
-
-	for (int i = 0; i < argsCount; ++i)
-	{
-		if (args[i]->isNull())
-		{
-			result->makeNullString();
-			return;
-		}
-
-		if (args[i]->isNullable())
-			isNullable = true;
-	}
+	bool isNullable;
+	if (initResult(result, argsCount, args, &isNullable))
+		return;
 
 	const dsc* value1 = args[0];
 	const dsc* value2 = (argsCount >= 3 ? args[2] : NULL);
@@ -783,8 +743,8 @@ static dsc* evlAsciiChar(Jrd::thread_db* tdbb, SysFunction* function, Jrd::jrd_n
 	if (!(code >= 0 && code <= 255))
 		status_exception::raise(isc_arith_except, 0);
 
-	impure->vlu_misc.vlu_char = (SCHAR) code;
-	impure->vlu_desc.makeText(1, ttype_none, (UCHAR*) &impure->vlu_misc.vlu_char);
+	impure->vlu_misc.vlu_uchar = (UCHAR) code;
+	impure->vlu_desc.makeText(1, ttype_none, &impure->vlu_misc.vlu_uchar);
 
 	return &impure->vlu_desc;
 }
diff --git a/src/jrd/exe.h b/src/jrd/exe.h
index 3232242f54..1ee35fb6d7 100644
--- a/src/jrd/exe.h
+++ b/src/jrd/exe.h
@@ -207,7 +207,7 @@ struct impure_value {
 	USHORT vlu_flags; // Computed/invariant flags
 	VaryingString* vlu_string;
 	union {
-		SCHAR vlu_char;
+		UCHAR vlu_uchar;
 		SSHORT vlu_short;
 		SLONG vlu_long;
 		SINT64 vlu_int64;
@@ -500,6 +500,7 @@ const int e_domval_length		= sizeof (DSC) / sizeof(::Jrd::jrd_nod*);	// Room for
 // System function expression
 const int e_sysfun_args		= 0;
 const int e_sysfun_function	= 1;
+const int e_sysfun_count	= 1;
 const int e_sysfun_length	= 2;
 
 // Request resources
diff --git a/src/jrd/par.cpp b/src/jrd/par.cpp
index afb96b949e..4f85041b08 100644
--- a/src/jrd/par.cpp
+++ b/src/jrd/par.cpp
@@ -2457,7 +2457,7 @@ static jrd_nod* par_sys_function(thread_db* tdbb, CompilerScratch* csb)
 	}
 
 	jrd_nod* node = PAR_make_node(tdbb, e_sysfun_length);
-	node->nod_count = 1;
+	node->nod_count = count_table[blr_sys_function];
 	node->nod_arg[e_sysfun_args] = par_args(tdbb, csb, VALUE);
 	node->nod_arg[e_sysfun_function] = (jrd_nod*) function;
 
diff --git a/src/misc/blrtable.cpp b/src/misc/blrtable.cpp
index c2b7c9cfa5..db8bd6fa30 100644
--- a/src/misc/blrtable.cpp
+++ b/src/misc/blrtable.cpp
@@ -218,7 +218,7 @@ static const VERB verbs[] =
 	PAIR(nod_strlen, blr_strlen, e_strlen_length, e_strlen_count, VALUE, VALUE),
 	PAIR(nod_trim, blr_trim, e_trim_length, e_trim_count, VALUE, VALUE),
 	PAIR(nod_init_variable, blr_init_variable, e_init_var_length, 0, STATEMENT, OTHER),
-	PAIR(nod_sys_function, blr_sys_function, 0, 0, VALUE, VALUE),
+	PAIR(nod_sys_function, blr_sys_function, e_sysfun_length, e_sysfun_count, VALUE, VALUE),
 	{0, NULL, NULL, NULL, NULL, NULL, NULL}
 };