diff --git a/src/oscompat.h b/src/oscompat.h
index 0b0c8b9..0e7a8db 100644
--- a/src/oscompat.h
+++ b/src/oscompat.h
@@ -44,7 +44,9 @@ static inline bool path_is_absolute(const char *path)
 #ifndef _WIN32
 	return path[0] == '/';
 #else
-	return (isalpha(path[0]) && path[1] == ':') ||
+	if (path[0] == '\0')
+		return false;
+	return (isalpha((unsigned char)path[0]) && path[1] == ':') ||
 	       (path[0] == '\\' && path[1] == '\\');
 #endif
 }
diff --git a/tests/test_oscompat.c b/tests/test_oscompat.c
index 9ee5bb2..189adbf 100644
--- a/tests/test_oscompat.c
+++ b/tests/test_oscompat.c
@@ -39,7 +39,13 @@ static void rmtree(const char *path)
 			if (!strcmp(ent->d_name, ".") || !strcmp(ent->d_name, ".."))
 				continue;
 
-			snprintf(child, sizeof(child), "%s/%s", path, ent->d_name);
+			if (snprintf(child, sizeof(child), "%s/%s", path,
+				     ent->d_name) >= (int)sizeof(child)) {
+				fprintf(stderr,
+					"skipping overly-long path %s/%s\n",
+					path, ent->d_name);
+				continue;
+			}
 			if (stat(child, &st) == 0 && S_ISDIR(st.st_mode))
 				rmtree(child);
 			else