diff --git a/src/mp-unitsConfig.cmake b/src/mp-unitsConfig.cmake
index 654150de..b42e3b55 100644
--- a/src/mp-unitsConfig.cmake
+++ b/src/mp-unitsConfig.cmake
@@ -22,7 +22,7 @@
 
 include(CMakeFindDependencyMacro)
 
-if(MP_UNITS_API_STD_FORMAT)
+if(NOT MP_UNITS_API_STD_FORMAT)
     find_dependency(fmt)
 endif()