diff --git a/test/date_test/durations.pass.cpp b/test/date_test/durations.pass.cpp
index e0c8245..70a152b 100644
--- a/test/date_test/durations.pass.cpp
+++ b/test/date_test/durations.pass.cpp
@@ -42,50 +42,17 @@
 
 #include <type_traits>
 
-static_assert(date::days{1} == std::chrono::seconds{86400}, "");
 static_assert(date::days{1} == std::chrono::hours{24}, "");
-static_assert( std::is_convertible<date::days, std::chrono::seconds>{}, "");
-static_assert( std::is_convertible<date::days, std::chrono::minutes>{}, "");
-static_assert( std::is_convertible<date::days, std::chrono::hours>{}, "");
-static_assert(!std::is_convertible<date::days, date::weeks>{}, "");
-static_assert(!std::is_convertible<date::days, date::months>{}, "");
-static_assert(!std::is_convertible<date::days, date::years>{}, "");
 
-static_assert(date::weeks{1} == std::chrono::seconds{604800}, "");
 static_assert(date::weeks{1} == date::days{7}, "");
-static_assert( std::is_convertible<date::weeks, std::chrono::seconds>{}, "");
-static_assert( std::is_convertible<date::weeks, std::chrono::minutes>{}, "");
-static_assert( std::is_convertible<date::weeks, std::chrono::hours>{}, "");
-static_assert( std::is_convertible<date::weeks, date::days>{}, "");
-static_assert(!std::is_convertible<date::weeks, date::months>{}, "");
-static_assert(!std::is_convertible<date::weeks, date::years>{}, "");
 
-static_assert(date::months{1} == std::chrono::seconds{2629746}, "");
+static_assert(date::months{12} == date::years{1}, "");
 static_assert(date::days{30} < date::months{1} && date::months{1} < date::days{31}, "");
 static_assert(date::weeks{4} < date::months{1} && date::months{1} < date::weeks{5}, "");
-static_assert(!std::is_convertible<date::months, date::years>{}, "");
-static_assert(!std::is_convertible<date::months, date::weeks>{}, "");
-static_assert(!std::is_convertible<date::months, date::days>{}, "");
-static_assert(!std::is_convertible<date::months, std::chrono::hours>{}, "");
-static_assert(!std::is_convertible<date::months, std::chrono::minutes>{}, "");
-static_assert( std::is_convertible<date::months, std::chrono::seconds>{}, "");
-static_assert( std::is_convertible<date::months, std::chrono::milliseconds>{}, "");
-static_assert( std::is_convertible<date::months, std::chrono::microseconds>{}, "");
-static_assert( std::is_convertible<date::months, std::chrono::nanoseconds>{}, "");
 
-static_assert(date::years{1} == std::chrono::seconds{31556952}, "");
+static_assert(date::years{400} == date::days{146097}, "");
 static_assert(date::days{365} < date::years{1} && date::years{1} < date::days{366}, "");
 static_assert(date::weeks{52} < date::years{1} && date::years{1} < date::weeks{53}, "");
-static_assert(date::years{1} == date::months{12}, "");
-static_assert( std::is_convertible<date::years, date::months>{}, "");
-static_assert(!std::is_convertible<date::years, date::weeks>{}, "");
-static_assert(!std::is_convertible<date::years, date::days>{}, "");
-static_assert(!std::is_convertible<date::years, std::chrono::hours>{}, "");
-static_assert(!std::is_convertible<date::years, std::chrono::minutes>{}, "");
-static_assert( std::is_convertible<date::years, std::chrono::seconds>{}, "");
-static_assert( std::is_convertible<date::years, std::chrono::milliseconds>{}, "");
-static_assert( std::is_convertible<date::years, std::chrono::microseconds>{}, "");
-static_assert( std::is_convertible<date::years, std::chrono::nanoseconds>{}, "");
 
 static_assert(std::is_same<date::day_point::duration, date::days>{}, "");