diff --git a/src/dawn_node/binding/GPU.cpp b/src/dawn_node/binding/GPU.cpp
index c4ba2a328b..cf22465ec3 100644
--- a/src/dawn_node/binding/GPU.cpp
+++ b/src/dawn_node/binding/GPU.cpp
@@ -31,7 +31,10 @@ namespace {
         }
         return "";
 #else
-        return std::getenv(varName);
+        if (auto* val = std::getenv(varName)) {
+            return val;
+        }
+        return "";
 #endif
     }
 }  // namespace
@@ -81,7 +84,8 @@ namespace wgpu { namespace binding {
 
         // Check for override from env var
         std::string envVar = getEnvVar("DAWNNODE_BACKEND");
-        std::transform(envVar.begin(), envVar.end(), envVar.begin(), std::tolower);
+        std::transform(envVar.begin(), envVar.end(), envVar.begin(),
+                       [](char c) { return std::tolower(c); });
         if (envVar == "null") {
             targetBackendType = wgpu::BackendType::Null;
         } else if (envVar == "webgpu") {