Index: src/fileio_func.h
===================================================================
--- src/fileio_func.h	(revision 19775)
+++ src/fileio_func.h	(working copy)
@@ -57,7 +57,7 @@
 char *FioGetDirectory(char *buf, size_t buflen, Subdirectory subdir);
 
 void SanitizeFilename(char *filename);
-void AppendPathSeparator(char *buf, size_t buflen);
+bool AppendPathSeparator(char *buf, size_t buflen);
 void DeterminePaths(const char *exe);
 void *ReadFileToMem(const char *filename, size_t *lenp, size_t maxsize);
 bool FileExists(const char *filename);
Index: src/os/unix/unix.cpp
===================================================================
--- src/os/unix/unix.cpp	(revision 19775)
+++ src/os/unix/unix.cpp	(working copy)
@@ -92,18 +92,21 @@
 bool FiosIsValidFile(const char *path, const struct dirent *ent, struct stat *sb)
 {
 	char filename[MAX_PATH];
-
+	int res;
 #if defined(__MORPHOS__) || defined(__AMIGAOS__)
 	/* On MorphOS or AmigaOS paths look like: "Volume:directory/subdirectory" */
 	if (FiosIsRoot(path)) {
-		snprintf(filename, lengthof(filename), "%s:%s", path, ent->d_name);
+		res = snprintf(filename, lengthof(filename), "%s:%s", path, ent->d_name);
 	} else // XXX - only next line!
 #else
 	assert(path[strlen(path) - 1] == PATHSEPCHAR);
 	if (strlen(path) > 2) assert(path[strlen(path) - 2] != PATHSEPCHAR);
 #endif
-	snprintf(filename, lengthof(filename), "%s%s", path, ent->d_name);
+	res = snprintf(filename, lengthof(filename), "%s%s", path, ent->d_name);
 
+	/* Could we fully concatenate the path and filename? */
+	if (res >= (int)lengthof(filename) || res < 0) return false;
+
 	return stat(filename, sb) == 0;
 }
 
Index: src/fileio.cpp
===================================================================
--- src/fileio.cpp	(revision 19775)
+++ src/fileio.cpp	(working copy)
@@ -448,16 +448,21 @@
  * It does not add the path separator to zero-sized strings.
  * @param buf    string to append the separator to
  * @param buflen the length of the buf
+ * @return true iff the operation succeeded
  */
-void AppendPathSeparator(char *buf, size_t buflen)
+bool AppendPathSeparator(char *buf, size_t buflen)
 {
 	size_t s = strlen(buf);
 
 	/* Length of string + path separator + '\0' */
-	if (s != 0 && buf[s - 1] != PATHSEPCHAR && s + 2 < buflen) {
+	if (s != 0 && buf[s - 1] != PATHSEPCHAR) {
+		if (s + 2 >= buflen) return false;
+
 		buf[s]     = PATHSEPCHAR;
 		buf[s + 1] = '\0';
 	}
+
+	return true;
 }
 
 /**
@@ -842,7 +847,7 @@
 		if (S_ISDIR(sb.st_mode)) {
 			/* Directory */
 			if (strcmp(d_name, ".") == 0 || strcmp(d_name, "..") == 0) continue;
-			AppendPathSeparator(filename, lengthof(filename));
+			if (!AppendPathSeparator(filename, lengthof(filename))) continue;
 			num += ScanPathForTarFiles(filename, basepath_length);
 		} else if (S_ISREG(sb.st_mode)) {
 			/* File */
@@ -1158,7 +1163,7 @@
 			/* Directory */
 			if (!recursive) continue;
 			if (strcmp(d_name, ".") == 0 || strcmp(d_name, "..") == 0) continue;
-			AppendPathSeparator(filename, lengthof(filename));
+			if (!AppendPathSeparator(filename, lengthof(filename))) continue;
 			num += ScanPath(fs, extension, filename, basepath_length, recursive);
 		} else if (S_ISREG(sb.st_mode)) {
 			/* File */
@@ -1245,6 +1250,6 @@
 {
 	char path[MAX_PATH];
 	strecpy(path, directory, lastof(path));
-	AppendPathSeparator(path, lengthof(path));
+	if (!AppendPathSeparator(path, lengthof(path))) return 0;
 	return ScanPath(this, extension, path, strlen(path), recursive);
 }
Index: src/stdafx.h
===================================================================
--- src/stdafx.h	(revision 19775)
+++ src/stdafx.h	(working copy)
@@ -416,7 +416,13 @@
 	#define _stricmp strcasecmp
 #endif
 
-#if !defined(MAX_PATH)
+#if defined(MAX_PATH)
+	/* It's already defined, no need to override */
+#elif defined(PATH_MAX) && PATH_MAX > 0
+	/* Use the value from PATH_MAX, if it exists */
+	#define MAX_PATH PATH_MAX
+#else
+	/* If all else fails, hardcode something :( */
 	#define MAX_PATH 260
 #endif