diff --git a/uppsrc/Core/Format.cpp b/uppsrc/Core/Format.cpp
index 2c547e856..5287af534 100644
--- a/uppsrc/Core/Format.cpp
+++ b/uppsrc/Core/Format.cpp
@@ -551,6 +551,14 @@ String IntFormatter(const Formatting& f)
 	return q;
 }
 
+String Int64Formatter(const Formatting& f)
+{
+	StringBuffer q;
+	q.SetLength(1000);
+	q.SetLength(sprintf(q, '%' + f.format + f.id, (int64)f.arg));
+	return q;
+}
+
 String IntLowerAlphaFormatter(const Formatting& f)
 {
 	return FormatIntAlpha(f.arg, false);
@@ -804,6 +812,12 @@ void IntDoubleRegister(int type)
 	RegisterFormatter(type, "lx", &IntFormatter);
 	RegisterFormatter(type, "lX", &IntFormatter);
 
+	RegisterFormatter(type, "lld", &Int64Formatter);
+	RegisterFormatter(type, "lli", &Int64Formatter);
+	RegisterFormatter(type, "llo", &Int64Formatter);
+	RegisterFormatter(type, "llx", &Int64Formatter);
+	RegisterFormatter(type, "llX", &Int64Formatter);
+
 	RegisterFormatter(type, "e", &FloatFormatter);
 	RegisterFormatter(type, "E", &FloatFormatter);
 	RegisterFormatter(type, "f", &FloatFormatter);
diff --git a/uppsrc/Core/src.tpp/Format$en-us.tpp b/uppsrc/Core/src.tpp/Format$en-us.tpp
index a18dfdd85..9c364c93f 100644
--- a/uppsrc/Core/src.tpp/Format$en-us.tpp
+++ b/uppsrc/Core/src.tpp/Format$en-us.tpp
@@ -110,7 +110,7 @@ delimits the formatter`-id).&]
 [s0; &]
 [s0; Most printf formatters are supported:&]
 [s0; &]
-[s0; [* c d i o x X ld li lo lx lX e E f g G s]&]
+[s0; [* c d i o x X ld li lo lx lX lld lli llo llx llX e E f g G s]&]
 [s0; &]
 [s0; Please refer to printf documentation for the description.&]
 [s0; &]