diff --git a/cppformat/format.cc b/cppformat/format.cc
index 4fc7220b..0857965e 100644
--- a/cppformat/format.cc
+++ b/cppformat/format.cc
@@ -207,10 +207,15 @@ void format_error_code(fmt::Writer &out, int error_code,
   out.clear();
   static const char SEP[] = ": ";
   static const char ERROR_STR[] = "error ";
-  fmt::internal::IntTraits<int>::MainType ec_value = error_code;
   // Subtract 2 to account for terminating null characters in SEP and ERROR_STR.
   std::size_t error_code_size = sizeof(SEP) + sizeof(ERROR_STR) - 2;
-  error_code_size += fmt::internal::count_digits(ec_value);
+  typedef fmt::internal::IntTraits<int>::MainType MainType;
+  MainType abs_value = static_cast<MainType>(error_code);
+  if (internal::is_negative(error_code)) {
+    abs_value = 0 - abs_value;
+    ++error_code_size;
+  }
+  error_code_size += fmt::internal::count_digits(abs_value);
   if (message.size() <= fmt::internal::INLINE_BUFFER_SIZE - error_code_size)
     out << message << SEP;
   out << ERROR_STR << error_code;
diff --git a/test/format-impl-test.cc b/test/format-impl-test.cc
index 187dcbdf..9f9cc5dd 100644
--- a/test/format-impl-test.cc
+++ b/test/format-impl-test.cc
@@ -101,13 +101,21 @@ TEST(FormatTest, FormatErrorCode) {
     fmt::format_error_code(w, 42, prefix);
     EXPECT_EQ(msg, w.str());
   }
-  {
+  int codes[] = {42, -1};
+  for (std::size_t i = 0, n = sizeof(codes) / sizeof(*codes); i < n; ++i) {
+    // Test maximum buffer size.
+    msg = fmt::format("error {}", codes[i]);
     fmt::MemoryWriter w;
     std::string prefix(
         fmt::internal::INLINE_BUFFER_SIZE - msg.size() - sep.size(), 'x');
-    fmt::format_error_code(w, 42, prefix);
+    fmt::format_error_code(w, codes[i], prefix);
     EXPECT_EQ(prefix + sep + msg, w.str());
     std::size_t size = fmt::internal::INLINE_BUFFER_SIZE;
     EXPECT_EQ(size, w.size());
+    w.clear();
+    // Test with a message that doesn't fit into the buffer.
+    prefix += 'x';
+    fmt::format_error_code(w, codes[i], prefix);
+    EXPECT_EQ(msg, w.str());
   }
 }