diff --git a/include/openmc/output.h b/include/openmc/output.h
index 549d2ae32ba..940ea78ceb9 100644
--- a/include/openmc/output.h
+++ b/include/openmc/output.h
@@ -76,10 +76,14 @@ struct formatter<std::array<T, 2>> {
   }
 
   template<typename FormatContext>
-  auto format(const std::array<T, 2>& arr, FormatContext& ctx) const
+#if FMT_VERSION >= 110000 // Version 11.0.0 and above
+  auto format(const std::array<T, 2>& arr, FormatContext& ctx) const {
+#else // For versions below 11.0.0
+  auto format(const std::array<T, 2>& arr, FormatContext& ctx)
   {
+#endif
     return format_to(ctx.out(), "({}, {})", arr[0], arr[1]);
-  }
-};
+}
+}; // namespace fmt
 
 } // namespace fmt
diff --git a/include/openmc/position.h b/include/openmc/position.h
index e6939dc0e46..dc60ab35a04 100644
--- a/include/openmc/position.h
+++ b/include/openmc/position.h
@@ -221,12 +221,16 @@ namespace fmt {
 template<>
 struct formatter<openmc::Position> : formatter<std::string> {
   template<typename FormatContext>
-  auto format(const openmc::Position& pos, FormatContext& ctx) const
+#if FMT_VERSION >= 110000 // Version 11.0.0 and above
+  auto format(const openmc::Position& pos, FormatContext& ctx) const {
+#else // For versions below 11.0.0
+  auto format(const openmc::Position& pos, FormatContext& ctx)
   {
+#endif
     return formatter<std::string>::format(
       fmt::format("({}, {}, {})", pos.x, pos.y, pos.z), ctx);
-  }
-};
+}
+}; // namespace fmt
 
 } // namespace fmt