diff --git a/src/console_cmds.cpp b/src/console_cmds.cpp
index bf4ba9fd16..02b7e11b27 100644
--- a/src/console_cmds.cpp
+++ b/src/console_cmds.cpp
@@ -459,15 +459,14 @@ DEF_CONSOLE_CMD(ConSave)
 	}
 
 	if (argc == 2) {
-		char *filename = str_fmt("%s.sav", argv[1]);
+		std::string filename = stdstr_fmt("%s.sav", argv[1]);
 		IConsolePrint(CC_DEFAULT, "Saving map...");
 
 		if (SaveOrLoad(filename, SLO_SAVE, DFT_GAME_FILE, SAVE_DIR) != SL_OK) {
 			IConsolePrint(CC_ERROR, "Saving map failed");
 		} else {
-			IConsolePrintF(CC_DEFAULT, "Map successfully saved to %s", filename);
+			IConsolePrintF(CC_DEFAULT, "Map successfully saved to %s", filename.c_str());
 		}
-		free(filename);
 		return true;
 	}
 
diff --git a/src/debug.cpp b/src/debug.cpp
index 462e969be4..593b8e9b6e 100644
--- a/src/debug.cpp
+++ b/src/debug.cpp
@@ -173,18 +173,16 @@ void debug_print(const char *dbg, const char *buf)
 			have_inited = true;
 			unsigned int num = 0;
 			int pid = getpid();
-			const char *fn = nullptr;
 			for(;;) {
 				free(fn);
-				fn = str_fmt("random-out-%d-%u.log", pid, num);
-				f = FioFOpenFile(fn, "wx", AUTOSAVE_DIR);
+				std::string fn = stdstr_fmt("random-out-%d-%u.log", pid, num);
+				f = FioFOpenFile(fn.c_str(), "wx", AUTOSAVE_DIR);
 				if (f == nullptr && errno == EEXIST) {
 					num++;
 					continue;
 				}
 				break;
 			}
-			free(fn);
 		}
 #else
 		static FILE *f = FioFOpenFile("random-out.log", "wb", AUTOSAVE_DIR);
diff --git a/src/pathfinder/yapf/yapf_rail.cpp b/src/pathfinder/yapf/yapf_rail.cpp
index 3d4213e25e..da0cb00d4d 100644
--- a/src/pathfinder/yapf/yapf_rail.cpp
+++ b/src/pathfinder/yapf/yapf_rail.cpp
@@ -34,26 +34,23 @@ template <typename Tpf> void DumpState(Tpf &pf1, Tpf &pf2)
 #if defined(UNIX) && defined(__GLIBC__)
 	static unsigned int num = 0;
 	int pid = getpid();
-	const char *fn1 = nullptr;
-	const char *fn2 = nullptr;
+	std::string fn1;
+	std::string fn2;
 	FILE *f1 = nullptr;
 	FILE *f2 = nullptr;
 	for(;;) {
-		free(fn1);
-		fn1 = str_fmt("yapf-%d-%u-1.txt", pid, num);
-		f1 = fopen(fn1, "wx");
+		fn1 = stdstr_fmt("yapf-%d-%u-1.txt", pid, num);
+		f1 = fopen(fn1.c_str(), "wx");
 		if (f1 == nullptr && errno == EEXIST) {
 			num++;
 			continue;
 		}
-		fn2 = str_fmt("yapf-%d-%u-2.txt", pid, num);
-		f2 = fopen(fn2, "w");
+		fn2 = stdstr_fmt("yapf-%d-%u-2.txt", pid, num);
+		f2 = fopen(fn2.c_str(), "w");
 		num++;
 		break;
 	}
-	DEBUG(desync, 0, "Dumping YAPF state to %s and %s", fn1, fn2);
-	free(fn1);
-	free(fn2);
+	DEBUG(desync, 0, "Dumping YAPF state to %s and %s", fn1.c_str(), fn2.c_str());
 #else
 	FILE *f1 = fopen("yapf1.txt", "wt");
 	FILE *f2 = fopen("yapf2.txt", "wt");
diff --git a/src/string.cpp b/src/string.cpp
index e6ccc68c43..d5939ce885 100644
--- a/src/string.cpp
+++ b/src/string.cpp
@@ -138,30 +138,6 @@ char *stredup(const char *s, const char *last)
 	return tmp;
 }
 
-char *str_vfmt(const char *str, va_list va)
-{
-	char buf[4096];
-
-	int len = vseprintf(buf, lastof(buf), str, va);
-	char *p = MallocT<char>(len + 1);
-	memcpy(p, buf, len + 1);
-	return p;
-}
-
-/**
- * Format, "printf", into a newly allocated string.
- * @param str The formatting string.
- * @return The formatted string. You must free this!
- */
-char *CDECL str_fmt(const char *str, ...)
-{
-	va_list va;
-	va_start(va, str);
-	char *output = str_vfmt(str, va);
-	va_end(va);
-	return output;
-}
-
 std::string stdstr_vfmt(const char *str, va_list va)
 {
 	char buf[4096];
diff --git a/src/string_func.h b/src/string_func.h
index 9f64e6b398..16c8c3c0a6 100644
--- a/src/string_func.h
+++ b/src/string_func.h
@@ -37,8 +37,6 @@ char *stredup(const char *src, const char *last = nullptr) NOACCESS(2);
 int CDECL seprintf(char *str, const char *last, const char *format, ...) WARN_FORMAT(3, 4) NOACCESS(2);
 int CDECL vseprintf(char *str, const char *last, const char *format, va_list ap) WARN_FORMAT(3, 0) NOACCESS(2);
 
-char *CDECL str_fmt(const char *str, ...) WARN_FORMAT(1, 2);
-char *str_vfmt(const char *str, va_list ap) WARN_FORMAT(1, 0);
 std::string CDECL stdstr_fmt(const char *str, ...) WARN_FORMAT(1, 2);
 std::string stdstr_vfmt(const char *str, va_list va) WARN_FORMAT(1, 0);