diff --git a/format.cc b/format.cc
index a4c9cee6..5a764a84 100644
--- a/format.cc
+++ b/format.cc
@@ -66,8 +66,10 @@ using fmt::internal::Arg;
 #ifndef FMT_THROW
 # if FMT_EXCEPTIONS
 #  define FMT_THROW(x) throw x
+#  define FMT_RETURNAFTERTHROW(x)
 # else
 #  define FMT_THROW(x) assert(false)
+#  define FMT_RETURNAFTERTHROW(x) return x
 # endif
 #endif
 
@@ -251,7 +253,7 @@ class WidthHandler : public fmt::internal::ArgVisitor<WidthHandler, unsigned> {
 
   unsigned visit_unhandled_arg() {
     FMT_THROW(fmt::FormatError("width is not integer"));
-    return 0;
+    FMT_RETURNAFTERTHROW(0);
   }
 
   template <typename T>
@@ -273,7 +275,7 @@ class PrecisionHandler :
  public:
   unsigned visit_unhandled_arg() {
     FMT_THROW(fmt::FormatError("precision is not integer"));
-    return 0;
+    FMT_RETURNAFTERTHROW(0);
   }
 
   template <typename T>
@@ -625,7 +627,7 @@ void fmt::BasicWriter<Char>::write_str(
     if (*str_value)
       str_size = std::char_traits<StrChar>::length(str_value);
   }
-  if (spec.precision_ >= 0 && spec.precision_ < str_size)
+  if (spec.precision_ >= 0 && static_cast<std::size_t>(spec.precision_) < str_size)
     str_size = spec.precision_;
   write_str(str_value, str_size, spec);
 }
diff --git a/format.h b/format.h
index 2baa259a..86485dcb 100644
--- a/format.h
+++ b/format.h
@@ -60,6 +60,16 @@
 # define FMT_GCC_EXTENSION
 #endif
 
+#define FMT_CLANGFALLTHROUGH
+
+#ifdef __clang__
+	#pragma clang diagnostic ignored "-Wdocumentation-unknown-command"
+	#ifdef NDEBUG
+		#undef FMT_CLANGFALLTHROUGH
+		#define FMT_CLANGFALLTHROUGH [[clang::fallthrough]];
+	#endif
+#endif
+
 #ifdef __GNUC_LIBSTD__
 # define FMT_GNUC_LIBSTD_VERSION (__GNUC_LIBSTD__ * 100 + __GNUC_LIBSTD_MINOR__)
 #endif
@@ -865,7 +875,8 @@ class ArgVisitor {
     default:
       assert(false);
       // Fall through.
-    case Arg::INT:
+		FMT_CLANGFALLTHROUGH
+	 case Arg::INT:
       return FMT_DISPATCH(visit_int(arg.int_value));
     case Arg::UINT:
       return FMT_DISPATCH(visit_uint(arg.uint_value));
@@ -2442,6 +2453,10 @@ FMT_VARIADIC(int, fprintf, std::FILE *, StringRef)
 # pragma GCC diagnostic pop
 #endif
 
+#ifdef __clang__
+# pragma clang diagnostic pop
+#endif
+
 #ifdef FMT_HEADER_ONLY
 # include "format.cc"
 #endif