diff --git a/src/include/units/base_dimension.h b/src/include/units/base_dimension.h
index 2df37dc4..bdf19e77 100644
--- a/src/include/units/base_dimension.h
+++ b/src/include/units/base_dimension.h
@@ -57,12 +57,21 @@ struct base_dimension {
 // BaseDimension
 namespace detail {
 
+#if __GNUC__ == 9 && __GNUC_MINOR__ < 2
+
+template<typename T>
+inline constexpr bool is_base_dimension = true;
+
+#else
+
 template<typename T>
 inline constexpr bool is_base_dimension = false;
 
 template<basic_fixed_string Name, typename... Params>
 inline constexpr bool is_base_dimension<base_dimension<Name, Params...>> = true;
 
+#endif
+
 }  // namespace detail
 
 template<typename T>