diff --git a/reactos/sdk/include/ndk/rtlfuncs.h b/reactos/sdk/include/ndk/rtlfuncs.h
index 9878369ec2b..30b61ed761f 100644
--- a/reactos/sdk/include/ndk/rtlfuncs.h
+++ b/reactos/sdk/include/ndk/rtlfuncs.h
@@ -2967,7 +2967,7 @@ NTSTATUS
 NTAPI
 RtlQueryEnvironmentVariable_U(
     _In_opt_ PWSTR Environment,
-    _In_ PUNICODE_STRING Name,
+    _In_ PCUNICODE_STRING Name,
     _Out_ PUNICODE_STRING Value
 );
 
diff --git a/reactos/sdk/lib/rtl/env.c b/reactos/sdk/lib/rtl/env.c
index 2db97555382..6bca1417581 100644
--- a/reactos/sdk/lib/rtl/env.c
+++ b/reactos/sdk/lib/rtl/env.c
@@ -508,7 +508,7 @@ found:
  */
 NTSTATUS NTAPI
 RtlQueryEnvironmentVariable_U(PWSTR Environment,
-                              PUNICODE_STRING Name,
+                              PCUNICODE_STRING Name,
                               PUNICODE_STRING Value)
 {
    NTSTATUS Status;