diff --git a/src/node_env_var.cc b/src/node_env_var.cc
index 5f543a5e76a1f9..8eaf79538a26e7 100644
--- a/src/node_env_var.cc
+++ b/src/node_env_var.cc
@@ -121,7 +121,7 @@ void RealEnvStore::Set(Isolate* isolate,
   node::Utf8Value val(isolate, value);
 
 #ifdef _WIN32
-  if (key[0] == L'=') return;
+  if (key.length() > 0 && key[0] == '=') return;
 #endif
   uv_os_setenv(*key, *val);
   DateTimeConfigurationChangeNotification(isolate, key);
@@ -139,7 +139,7 @@ int32_t RealEnvStore::Query(const char* key) const {
   }
 
 #ifdef _WIN32
-  if (key[0] == L'=') {
+  if (key[0] == '=') {
     return static_cast<int32_t>(v8::ReadOnly) |
            static_cast<int32_t>(v8::DontDelete) |
            static_cast<int32_t>(v8::DontEnum);
@@ -227,7 +227,7 @@ void MapKVStore::Set(Isolate* isolate, Local<String> key, Local<String> value) {
   Mutex::ScopedLock lock(mutex_);
   Utf8Value key_str(isolate, key);
   Utf8Value value_str(isolate, value);
-  if (*key_str != nullptr && *value_str != nullptr) {
+  if (*key_str != nullptr && key_str.length() > 0 && *value_str != nullptr) {
     map_[std::string(*key_str, key_str.length())] =
         std::string(*value_str, value_str.length());
   }
diff --git a/test/parallel/test-process-env.js b/test/parallel/test-process-env.js
index 0e06306634c3e2..4ece826e8b938f 100644
--- a/test/parallel/test-process-env.js
+++ b/test/parallel/test-process-env.js
@@ -106,3 +106,11 @@ if (common.isWindows) {
   const keys = Object.keys(process.env);
   assert.ok(keys.length > 0);
 }
+
+// Setting environment variables on Windows with empty names should not cause
+// an assertion failure.
+// https://github.com/nodejs/node/issues/32920
+{
+  process.env[''] = '';
+  assert.strictEqual(process.env[''], undefined);
+}