diff --git a/0001-Fix-charconv-support-with-MSVC-GCC11.patch b/0001-Fix-charconv-support-with-MSVC-GCC11.patch
new file mode 100644
index 0000000..fcdf094
--- /dev/null
+++ b/0001-Fix-charconv-support-with-MSVC-GCC11.patch
@@ -0,0 +1,43 @@
+From 1e8e6c8da1e22c4d32e50d8999705fd370824736 Mon Sep 17 00:00:00 2001
+From: "L. E. Segovia" <amy@amyspark.me>
+Date: Tue, 1 Jun 2021 23:35:40 +0000
+Subject: [PATCH] Fix charconv support with MSVC/GCC11
+
+BUG: 437890
+---
+ src/KSeExpr/Utils.cpp | 5 +++--
+ 1 file changed, 3 insertions(+), 2 deletions(-)
+
+diff --git a/src/KSeExpr/Utils.cpp b/src/KSeExpr/Utils.cpp
+index 22e6cd8..e48cfe9 100644
+--- a/src/KSeExpr/Utils.cpp
++++ b/src/KSeExpr/Utils.cpp
+@@ -6,6 +6,7 @@
+ 
+ #if defined(KSeExpr_HAVE_CHARCONV_WITH_DOUBLES)
+ #include <charconv>
++#include <cstring>
+ 
+ double_t KSeExpr::Utils::atof(const char *num)
+ {
+@@ -21,7 +22,7 @@ double_t KSeExpr::Utils::atof(const char *num)
+ double_t KSeExpr::Utils::atof(const std::string &num)
+ {
+     double_t v;
+-    auto [p, ec] = std::from_chars(val.data(), val.data() + val.size(), v);
++    auto [p, ec] = std::from_chars(num.data(), num.data() + num.size(), v);
+     if (ec == std::errc()) {
+         return v;
+     } else {
+@@ -32,7 +33,7 @@ double_t KSeExpr::Utils::atof(const std::string &num)
+ int32_t KSeExpr::Utils::strtol(const std::string &num)
+ {
+     int32_t v;
+-    auto [p, ec] = std::from_chars(val.data(), val.data() + val.size(), v);
++    auto [p, ec] = std::from_chars(num.data(), num.data() + num.size(), v);
+     if (ec == std::errc()) {
+         return v;
+     } else if (ec == std::errc::result_out_of_range) {
+-- 
+2.31.1
+
diff --git a/kseexpr.changes b/kseexpr.changes
index 84779e8..c677fe4 100644
--- a/kseexpr.changes
+++ b/kseexpr.changes
@@ -1,3 +1,9 @@
+-------------------------------------------------------------------
+Wed Jun  2 06:04:23 UTC 2021 - Christophe Giboudeaux <christophe@krop.fr>
+
+- Add GCC 11 build fix (kde#437890):
+  * 0001-Fix-charconv-support-with-MSVC-GCC11.patch
+
 -------------------------------------------------------------------
 Wed Jan 13 12:42:40 UTC 2021 - Wolfgang Bauer <wbauer@tmo.at>
 
diff --git a/kseexpr.spec b/kseexpr.spec
index 7b17c92..449ab0b 100644
--- a/kseexpr.spec
+++ b/kseexpr.spec
@@ -34,6 +34,8 @@ Source0:        https://download.kde.org/stable/%{name}/4.0.1/%{name}-%{version}
 Patch0:         Fix-translation-lookup-in-stock-Linux-deployments.patch
 # PATCH-FIX-OPENSUSE
 Patch1:         Fix-possible-compiler-error.patch
+# PATCH-FIX-UPSTREAM
+Patch2:         0001-Fix-charconv-support-with-MSVC-GCC11.patch
 BuildRequires:  extra-cmake-modules
 BuildRequires:  cmake(Qt5Core)
 BuildRequires:  cmake(Qt5Gui)