diff --git a/include/fmt/color.h b/include/fmt/color.h
index 8de5b294..362a95e1 100644
--- a/include/fmt/color.h
+++ b/include/fmt/color.h
@@ -299,15 +299,15 @@ class text_style {
     return static_cast<uint8_t>(ems) != 0;
   }
   FMT_CONSTEXPR internal::color_type get_foreground() const FMT_NOEXCEPT {
-    assert(has_foreground() && "no foreground specified for this style");
+    FMT_ASSERT(has_foreground(), "no foreground specified for this style");
     return foreground_color;
   }
   FMT_CONSTEXPR internal::color_type get_background() const FMT_NOEXCEPT {
-    assert(has_background() && "no background specified for this style");
+    FMT_ASSERT(has_background(), "no background specified for this style");
     return background_color;
   }
   FMT_CONSTEXPR emphasis get_emphasis() const FMT_NOEXCEPT {
-    assert(has_emphasis() && "no emphasis specified for this style");
+    FMT_ASSERT(has_emphasis(), "no emphasis specified for this style");
     return ems;
   }
 
diff --git a/include/fmt/core.h b/include/fmt/core.h
index 80869b82..346f7616 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -8,7 +8,6 @@
 #ifndef FMT_CORE_H_
 #define FMT_CORE_H_
 
-#include <cassert>
 #include <cstdio>  // std::FILE
 #include <cstring>
 #include <iterator>
@@ -187,10 +186,6 @@
 #  define FMT_EXTERN
 #endif
 
-#ifndef FMT_ASSERT
-#  define FMT_ASSERT(condition, message) assert((condition) && (message))
-#endif
-
 // libc++ supports string_view in pre-c++17.
 #if (FMT_HAS_INCLUDE(<string_view>) &&                       \
      (__cplusplus > 201402L || defined(_LIBCPP_VERSION))) || \
@@ -229,6 +224,18 @@ namespace internal {
 // A workaround for gcc 4.8 to make void_t work in a SFINAE context.
 template <typename... Ts> struct void_t_impl { using type = void; };
 
+void assert_fail(const char* file, int line, const char* message);
+
+#ifndef FMT_ASSERT
+#  ifdef NDEBUG
+#    define FMT_ASSERT(condition, message)
+#  else
+#    define FMT_ASSERT(condition, message) \
+      if (!(condition))                    \
+      fmt::internal::assert_fail(__FILE__, __LINE__, (message))
+#  endif
+#endif
+
 #if defined(FMT_USE_STRING_VIEW)
 template <typename Char> using std_string_view = std::basic_string_view<Char>;
 #elif defined(FMT_USE_EXPERIMENTAL_STRING_VIEW)
diff --git a/include/fmt/format-inl.h b/include/fmt/format-inl.h
index 9c8e0816..99ad5528 100644
--- a/include/fmt/format-inl.h
+++ b/include/fmt/format-inl.h
@@ -10,8 +10,7 @@
 
 #include "format.h"
 
-#include <cstring>
-
+#include <cassert>
 #include <cctype>
 #include <cerrno>
 #include <climits>
@@ -57,6 +56,11 @@ inline fmt::internal::null<> strerror_s(char*, std::size_t, ...) { return {}; }
 FMT_BEGIN_NAMESPACE
 namespace internal {
 
+FMT_FUNC void assert_fail(const char* file, int line, const char* message) {
+  print(stderr, "{}:{}: assertion failed: {}", file, line, message);
+  std::abort();
+}
+
 #ifndef _MSC_VER
 #  define FMT_SNPRINTF snprintf
 #else  // _MSC_VER
diff --git a/include/fmt/format.h b/include/fmt/format.h
index 3a48f21f..76c5ea9d 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -220,7 +220,9 @@ inline Dest bit_cast(const Source& source) {
 
 inline bool is_big_endian() {
   auto u = 1u;
-  struct bytes { char data[sizeof(u)]; };
+  struct bytes {
+    char data[sizeof(u)];
+  };
   return bit_cast<bytes>(u).data[0] == 0;
 }
 
diff --git a/test/format b/test/format
index d110f3ec..db27614e 100644
--- a/test/format
+++ b/test/format
@@ -8,6 +8,7 @@
 #ifndef FMT_FORMAT_
 #define FMT_FORMAT_
 
+#include <cassert>
 #include <variant>
 #include "fmt/format.h"