diff --git a/qa/unittests/libs/kimath/CMakeLists.txt b/qa/unittests/libs/kimath/CMakeLists.txt
index 6c9cbf9ea3..6a73340538 100644
--- a/qa/unittests/libs/kimath/CMakeLists.txt
+++ b/qa/unittests/libs/kimath/CMakeLists.txt
@@ -40,6 +40,7 @@ set( KIMATH_SRCS
 
     math/test_vector2.cpp
     math/test_vector3.cpp
+    math/test_util.cpp
 )
 
 add_executable( qa_kimath ${KIMATH_SRCS} )
diff --git a/qa/unittests/libs/kimath/math/test_util.cpp b/qa/unittests/libs/kimath/math/test_util.cpp
new file mode 100644
index 0000000000..dfcd673c60
--- /dev/null
+++ b/qa/unittests/libs/kimath/math/test_util.cpp
@@ -0,0 +1,129 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2022 KiCad Developers, see AUTHORS.TXT for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+/**
+ * Test suite for KiCad math code.
+ */
+
+#include <qa_utils/wx_utils/unit_test_utils.h>
+#include <inttypes.h>
+
+// Code under test
+#include <math/util.h>
+
+struct TEST_RESCALE_I64_CASE
+{
+    int64_t m_numerator;
+    int64_t m_value;
+    int64_t m_denominator;
+    int64_t m_result;
+};
+
+/**
+ * Declare the test suite
+ */
+BOOST_AUTO_TEST_SUITE( MathUtil )
+
+BOOST_AUTO_TEST_CASE( test_rescale_int64 )
+{
+    // Order: numerator, value, denominator, result.
+    const std::vector<TEST_RESCALE_I64_CASE> rescale_i64_cases = {
+        { 10LL, 10LL, 1LL, 100LL },
+        { 10LL, 10LL, -1LL, -100LL },
+        { 10LL, -10LL, 1LL, -100LL },
+        { 10LL, -10LL, -1LL, 100LL },
+
+        { 1LL, 9LL, 1LL, 9LL },
+        { 1LL, 9LL, -1LL, -9LL },
+        { 1LL, -9LL, 1LL, -9LL },
+        { 1LL, -9LL, -1LL, 9LL },
+
+        { 10LL, 10LL, 2LL, 50LL },
+        { 10LL, 10LL, -2LL, -50LL },
+        { 10LL, -10LL, 2LL, -50LL },
+        { 10LL, -10LL, -2LL, 50LL },
+
+        { 1LL, 9LL, 2LL, 5LL },
+        { 1LL, 9LL, -2LL, -5LL },
+        { 1LL, -9LL, 2LL, -5LL },
+        { 1LL, -9LL, -2LL, 5LL },
+
+        { 1LL, 17LL, 4LL, 4LL },
+        { 1LL, 17LL, -4LL, -4LL },
+        { 1LL, -17LL, 4LL, -4LL },
+        { 1LL, -17LL, -4LL, 4LL },
+
+        { 1LL, 19LL, 4LL, 5LL },
+        { 1LL, 19LL, -4LL, -5LL },
+        { 1LL, -19LL, 4LL, -5LL },
+        { 1LL, -19LL, -4LL, 5LL },
+
+        { 1LL, 0LL, 4LL, 0LL },
+        { 1LL, 0LL, -4LL, 0LL },
+        { -1LL, 0LL, 4LL, 0LL },
+        { -1LL, 0LL, -4LL, 0LL },
+
+        // sqrt(2^63) = 3037000499.98..
+        { 3037000499LL, 3037000499LL, 1LL, 9223372030926249001LL },
+        { 3037000499LL, 3037000499LL, -1LL, -9223372030926249001LL },
+        { 3037000499LL, -3037000499LL, 1LL, -9223372030926249001LL },
+        { 3037000499LL, -3037000499LL, -1LL, 9223372030926249001LL },
+
+        // sqrt(2^63 * 10) = 9603838834.99..
+        { 9603838834LL, 9603838834LL, 10LL, 9223372034944647956LL },
+        { 9603838834LL, 9603838834LL, -10LL, -9223372034944647956LL },
+        { 9603838834LL, -9603838834LL, 10LL, -9223372034944647956LL },
+        { 9603838834LL, -9603838834LL, -10LL, 9223372034944647956LL },
+
+        // INT64_MAX = 9223372036854775807
+        { INT64_MAX, 10LL, 10LL, INT64_MAX },
+        { INT64_MAX, 10LL, -10LL, -INT64_MAX },
+        { INT64_MAX, -10LL, 10LL, -INT64_MAX },
+        { INT64_MAX, -10LL, -10LL, INT64_MAX },
+
+        { INT64_MAX, 10LL, INT64_MAX, 10LL },
+        { INT64_MAX, 10LL, -INT64_MAX, -10LL },
+        { INT64_MAX, -10LL, INT64_MAX, -10LL },
+        { INT64_MAX, -10LL, -INT64_MAX, 10LL },
+
+        { INT64_MAX, INT64_MAX, INT64_MAX, INT64_MAX },
+        { INT64_MAX, INT64_MAX, -INT64_MAX, -INT64_MAX },
+        { INT64_MAX, -INT64_MAX, INT64_MAX, -INT64_MAX },
+        { INT64_MAX, -INT64_MAX, -INT64_MAX, INT64_MAX },
+    };
+
+    for( const TEST_RESCALE_I64_CASE& entry : rescale_i64_cases )
+    {
+        int64_t  calculated = rescale( entry.m_numerator, entry.m_value, entry.m_denominator );
+        wxString msg;
+
+        msg << "rescale<int64_t>( " << entry.m_numerator << ", " << entry.m_value << ", "
+            << entry.m_denominator << " ) failed. ";
+        msg << "\nExpected: " << entry.m_result;
+        msg << "\nGot: " << calculated;
+
+        BOOST_CHECK_MESSAGE( calculated == entry.m_result, msg );
+    }
+}
+
+BOOST_AUTO_TEST_SUITE_END()