diff --git a/src/env.cpp b/src/env.cpp
index 77f65b7bc..fc00031f1 100644
--- a/src/env.cpp
+++ b/src/env.cpp
@@ -698,10 +698,36 @@ void env_set_read_limit() {
 
 wcstring env_get_pwd_slash() {
     auto pwd_var = env_get(L"PWD");
-    if (pwd_var.missing_or_empty()) {
-        return L"";
+    wcstring pwd;
+    if (!pwd_var.missing_or_empty()) {
+        pwd = pwd_var->as_string();
     }
-    wcstring pwd = pwd_var->as_string();
+    else {
+        // Not sure how we can end up here, but it's possible.
+        // See https://github.com/fish-shell/fish-shell/issues/5080
+        // Perhaps it can happen on some platforms if the path is too long?
+        std::vector<char> path;
+        bool cwd_success = false;
+        for (int i = 1; !cwd_success && i <= 10; ++i) {
+            path.resize(PATH_MAX * i);
+            if (getcwd(&path[0], PATH_MAX * i) == nullptr) {
+                if (errno == ERANGE) {
+                    // buffer is not big enough, try again (up to a point)
+                    continue;
+                }
+                debug(1, "getcwd() failed with errno %d", errno);
+                // . but with a trailing slash, because that's what this function does
+                return L"./";
+            }
+            cwd_success = true;
+        }
+        if (!cwd_success) {
+            debug(1, "getcwd() path too long!");
+            return L"./";
+        }
+        pwd = str2wcstring(path.data());
+    }
+
     if (!string_suffixes_string(L"/", pwd)) {
         pwd.push_back(L'/');
     }