diff --git a/src/systems/include/mp-units/systems/si/unit_symbols.h b/src/systems/include/mp-units/systems/si/unit_symbols.h
index 060bfb93..466c956c 100644
--- a/src/systems/include/mp-units/systems/si/unit_symbols.h
+++ b/src/systems/include/mp-units/systems/si/unit_symbols.h
@@ -318,6 +318,11 @@ inline constexpr auto YN = yotta<newton>;
 inline constexpr auto RN = ronna<newton>;
 inline constexpr auto QN = quetta<newton>;
 
+#ifdef pascal
+#pragma push_macro("pascal")
+#undef pascal
+#define MP_UNITS_REDEFINE_PASCAL
+#endif
 inline constexpr auto qPa = quecto<pascal>;
 inline constexpr auto rPa = ronto<pascal>;
 inline constexpr auto yPa = yocto<pascal>;
@@ -343,6 +348,10 @@ inline constexpr auto ZPa = zetta<pascal>;
 inline constexpr auto YPa = yotta<pascal>;
 inline constexpr auto RPa = ronna<pascal>;
 inline constexpr auto QPa = quetta<pascal>;
+#ifdef MP_UNITS_REDEFINE_PASCAL
+#pragma pop_macro("pascal")
+#undef MP_UNITS_REDEFINE_PASCAL
+#endif
 
 inline constexpr auto qJ = quecto<joule>;
 inline constexpr auto rJ = ronto<joule>;
diff --git a/src/systems/include/mp-units/systems/usc.h b/src/systems/include/mp-units/systems/usc.h
index ec16c71f..cca91973 100644
--- a/src/systems/include/mp-units/systems/usc.h
+++ b/src/systems/include/mp-units/systems/usc.h
@@ -115,7 +115,16 @@ inline constexpr struct troy_once final : named_unit<"oz t", mag<20> * pennyweig
 inline constexpr struct troy_pound final : named_unit<"lb t", mag<12> * troy_once> {} troy_pound;
 
 // https://en.wikipedia.org/wiki/Inch_of_mercury
+#ifdef pascal
+#pragma push_macro("pascal")
+#undef pascal
+#define MP_UNITS_REDEFINE_PASCAL
+#endif
 inline constexpr struct inch_of_mercury final : named_unit<"inHg", mag_ratio<3'386'389, 1'000> * si::pascal> {} inch_of_mercury;
+#ifdef MP_UNITS_REDEFINE_PASCAL
+#pragma pop_macro("pascal")
+#undef MP_UNITS_REDEFINE_PASCAL
+#endif
 
 // https://en.wikipedia.org/wiki/United_States_customary_units#Temperature
 inline constexpr struct zeroth_degree_Fahrenheit final : relative_point_origin<absolute<mag_ratio<5, 9> * si::degree_Celsius>(-32)> {} zeroth_degree_Fahrenheit;