diff --git a/common/main/player-callsign.h b/common/main/player-callsign.h
index 529f7bc3f..825a954a4 100644
--- a/common/main/player-callsign.h
+++ b/common/main/player-callsign.h
@@ -8,10 +8,10 @@
 
 #pragma once
 
-#ifdef __cplusplus
 #include <algorithm>
 #include <cctype>
 #include <cstddef>
+#include <span>
 #include "dxxsconf.h"
 #include <array>
 
@@ -28,10 +28,18 @@ struct callsign_t
 	{
 		return std::tolower(static_cast<unsigned>(c));
 	}
-	void copy(const char *s, std::size_t N)
+	template <std::size_t Extent>
+		requires(Extent == std::dynamic_extent || Extent <= array_length)
+	void copy(const std::span<const char, Extent> s)
 	{
+		/* Zero the entire array first, so that word-sized moves can be used to
+		 * store the null bytes in bulk.  Then copy an appropriate number of
+		 * characters using byte-sized moves, with a limit to prevent
+		 * overwriting the final null byte even if the input string is too
+		 * long.
+		 */
 		a = {};
-		std::copy_n(s, std::min(a.size() - 1, N), begin(a));
+		std::copy_n(s.data(), std::min(a.size() - 1, s.size()), begin(a));
 	}
 	void copy_lower(const char *s, std::size_t N)
 	{
@@ -52,8 +60,7 @@ struct callsign_t
 	template <std::size_t N>
 		void operator=(const char (&s)[N])
 		{
-			static_assert(N <= array_length, "string too long");
-			copy(s, N);
+			copy(std::span(s));
 		}
 	template <std::size_t N>
 		void copy_lower(const char (&s)[N])
@@ -80,5 +87,3 @@ struct callsign_t
 	}
 };
 static_assert(sizeof(callsign_t) == CALLSIGN_LEN + 1, "callsign_t too big");
-
-#endif
diff --git a/similar/main/inferno.cpp b/similar/main/inferno.cpp
index e08bdc7d1..7fc364935 100644
--- a/similar/main/inferno.cpp
+++ b/similar/main/inferno.cpp
@@ -726,7 +726,7 @@ static int main(int argc, char *argv[])
 			}
 			if(PHYSFSX_exists(filename,0))
 			{
-				InterfaceUniqueState.PilotName.copy(b, std::distance(b, &filename[j - 4]));
+				InterfaceUniqueState.PilotName.copy(std::span<const char>(b, std::distance(b, &filename[j - 4])));
 				InterfaceUniqueState.update_window_title();
 				read_player_file();
 				WriteConfigFile();
diff --git a/similar/main/net_udp.cpp b/similar/main/net_udp.cpp
index 6a3992857..4cdc3cbf6 100644
--- a/similar/main/net_udp.cpp
+++ b/similar/main/net_udp.cpp
@@ -204,8 +204,20 @@ net_udp_select_teams_menu_items::net_udp_select_teams_menu_items(const unsigned
 	blue_team_color(BM_XRGB(player_rgb[0].r, player_rgb[0].g, player_rgb[0].b)),
 	red_team_color(BM_XRGB(player_rgb[1].r, player_rgb[1].g, player_rgb[1].b))
 {
-	team_names[0].copy(TXT_BLUE, ~0ul);
-	team_names[1].copy(TXT_RED, ~0ul);
+	const auto set_team_name = [](callsign_t &team_name, const auto &&s) {
+		if constexpr (std::is_array<typename std::remove_cvref<decltype(s)>::type>::value)
+			/* When the input is an array (due to
+			 * -D'USE_BUILTIN_ENGLISH_TEXT_STRINGS'), construct a std::span
+			 *  implicitly with the correct length.
+			 */
+			team_name.copy(s);
+		else
+			/* Otherwise, construct one explicitly with the dynamically
+			 * detected length. */
+			team_name.copy(std::span(s, strlen(s)));
+	};
+	set_team_name(team_names[0], TXT_BLUE);
+	set_team_name(team_names[1], TXT_RED);
 	/* Round blue team up.  Round red team down. */
 	const unsigned num_blue_players = (num_players + 1) >> 1;
 	// Put first half of players on team A
@@ -3183,7 +3195,7 @@ static void net_udp_process_game_info_heavy(const uint8_t *data, uint_fast32_t,
 		Netgame.InvulAppear = data[len];				len += 1;
 		range_for (auto &i, Netgame.team_name)
 		{
-			i.copy(reinterpret_cast<const char *>(&data[len]), (CALLSIGN_LEN+1));
+			i.copy(std::span<const char, CALLSIGN_LEN + 1>(reinterpret_cast<const char *>(&data[len]), CALLSIGN_LEN + 1));
 			len += CALLSIGN_LEN + 1;
 		}
 		range_for (auto &i, Netgame.locations)