diff --git a/src/systems/usc/include/mp-units/systems/usc/usc.h b/src/systems/usc/include/mp-units/systems/usc/usc.h
index 98c1ea41..31d35c5b 100644
--- a/src/systems/usc/include/mp-units/systems/usc/usc.h
+++ b/src/systems/usc/include/mp-units/systems/usc/usc.h
@@ -110,7 +110,7 @@ inline constexpr struct troy_pound : named_unit<"lb t", mag<12> * troy_once> {}
 inline constexpr struct inch_of_mercury : named_unit<"inHg", mag<ratio(3'386'389, 1'000)> * si::pascal> {} inch_of_mercury;
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Temperature
-inline constexpr struct degree_Fahrenheit : named_unit<basic_symbol_text{"°F", "`F"}, mag<ratio{9, 5}> * si::degree_Celsius> {} degree_Fahrenheit;
+inline constexpr struct degree_Fahrenheit : named_unit<basic_symbol_text{"°F", "`F"}, mag<ratio{5, 9}> * si::degree_Celsius> {} degree_Fahrenheit;
 // clang-format on
 
 namespace unit_symbols {