diff --git a/GSL.natvis b/GSL.natvis
index e40a8c9..a467a17 100644
--- a/GSL.natvis
+++ b/GSL.natvis
@@ -11,7 +11,7 @@
     </Type>
 
     <!-- These types are from the gsl_util header. -->
-    <Type Name="gsl::final_act&lt;*&gt;">
+    <Type Name="gsl::final_action&lt;*&gt;">
         <DisplayString>{{ invoke = {invoke_}, action = {f_} }}</DisplayString>
         <Expand>
             <Item Name="[invoke]">invoke_</Item>
diff --git a/include/gsl/gsl_assert b/include/gsl/gsl_assert
index 468d4a0..eeb3473 100644
--- a/include/gsl/gsl_assert
+++ b/include/gsl/gsl_assert
@@ -52,12 +52,10 @@
 //
 #ifdef _MSC_VER
 #define GSL_ASSUME(cond) __assume(cond)
-#elif defined(__clang__)
-#define GSL_ASSUME(cond) __builtin_assume(cond)
 #elif defined(__GNUC__)
 #define GSL_ASSUME(cond) ((cond) ? static_cast<void>(0) : __builtin_unreachable())
 #else
-#define GSL_ASSUME(cond) static_cast<void>(!!(cond))
+#define GSL_ASSUME(cond) static_cast<void>((cond) ? 0 : 0)
 #endif
 
 //
diff --git a/include/gsl/string_span b/include/gsl/string_span
index 42f8975..0c9f2cf 100644
--- a/include/gsl/string_span
+++ b/include/gsl/string_span
@@ -98,7 +98,7 @@ namespace details
     {
         if (str == nullptr || n <= 0) return 0;
 
-        span<const CharT> str_span{str, n};
+        const span<const CharT> str_span{str, n};
 
         std::ptrdiff_t len = 0;
         while (len < n && str_span[len]) len++;