diff --git a/reactos/dll/win32/dnsapi/dnsapi/query.c b/reactos/dll/win32/dnsapi/dnsapi/query.c
index 5dbbadf757b..fc7f9337887 100644
--- a/reactos/dll/win32/dnsapi/dnsapi/query.c
+++ b/reactos/dll/win32/dnsapi/dnsapi/query.c
@@ -59,6 +59,9 @@ DnsQuery_A(LPCSTR Name,
     LPSTR CurrentName;
     unsigned i, CNameLoop;
 
+    if (Name == NULL)
+        return ERROR_INVALID_PARAMETER;
+
     *QueryResultSet = 0;
 
     switch(Type)
@@ -200,6 +203,9 @@ DnsQuery_W(LPCWSTR Name,
     PDNS_RECORD QueryResultWide;
     PDNS_RECORD ConvertedRecord = 0, LastRecord = 0;
 
+    if (Name == NULL)
+        return ERROR_INVALID_PARAMETER;
+
     Buffer = DnsWToC(Name);
 
     Status = DnsQuery_A(Buffer, Type, Options, Servers, &QueryResultWide, Reserved);