diff --git a/core/string/ustring.cpp b/core/string/ustring.cpp
index 1704bf52cc2..654f1671ecb 100644
--- a/core/string/ustring.cpp
+++ b/core/string/ustring.cpp
@@ -5262,7 +5262,11 @@ String String::sprintf(const Span<Variant> &values, bool *error) const {
 					// Get basic number.
 					String str;
 					if (!as_unsigned) {
-						str = String::num_int64(Math::abs(value), base, capitalize);
+						if (value == INT64_MIN) { // INT64_MIN can't be represented as positive value.
+							str = String::num_int64(value, base, capitalize).trim_prefix("-");
+						} else {
+							str = String::num_int64(Math::abs(value), base, capitalize);
+						}
 					} else {
 						uint64_t uvalue = *((uint64_t *)&value);
 						// In unsigned hex, if the value fits in 32 bits, trim it down to that.
diff --git a/tests/core/string/test_string.h b/tests/core/string/test_string.h
index 68183f52be7..de0ae8cc65c 100644
--- a/tests/core/string/test_string.h
+++ b/tests/core/string/test_string.h
@@ -992,6 +992,38 @@ TEST_CASE("[String] sprintf") {
 	REQUIRE(error == false);
 	CHECK(output == String("fish 143 frog"));
 
+	// INT64_MIN
+	format = "fish %d frog";
+	args.clear();
+	args.push_back(INT64_MIN);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish -9223372036854775808 frog"));
+
+	// INT64_MIN hex (lower)
+	format = "fish %x frog";
+	args.clear();
+	args.push_back(INT64_MIN);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish -8000000000000000 frog"));
+
+	// INT64_MIN hex (upper)
+	format = "fish %X frog";
+	args.clear();
+	args.push_back(INT64_MIN);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish -8000000000000000 frog"));
+
+	// INT64_MIN octal
+	format = "fish %o frog";
+	args.clear();
+	args.push_back(INT64_MIN);
+	output = format.sprintf(args, &error);
+	REQUIRE(error == false);
+	CHECK(output == String("fish -1000000000000000000000 frog"));
+
 	///// Reals
 
 	// Real