diff --git a/dlls/setupapi/devinst.c b/dlls/setupapi/devinst.c
index 9ad0c0318b0..645211a78b3 100644
--- a/dlls/setupapi/devinst.c
+++ b/dlls/setupapi/devinst.c
@@ -3181,6 +3181,11 @@ BOOL WINAPI SetupDiInstallClassA(
     UNICODE_STRING FileNameW;
     BOOL Result;
 
+    if (!InfFileName)
+    {
+        SetLastError(ERROR_INVALID_PARAMETER);
+        return FALSE;
+    }
     if (!RtlCreateUnicodeStringFromAsciiz(&FileNameW, InfFileName))
     {
         SetLastError(ERROR_NOT_ENOUGH_MEMORY);
@@ -3283,6 +3288,11 @@ BOOL WINAPI SetupDiInstallClassW(
 
     FIXME("\n");
 
+    if (!InfFileName)
+    {
+        SetLastError(ERROR_INVALID_PARAMETER);
+        return FALSE;
+    }
     if ((Flags & DI_NOVCP) && (FileQueue == NULL || FileQueue == INVALID_HANDLE_VALUE))
     {
 	SetLastError(ERROR_INVALID_PARAMETER);
diff --git a/dlls/setupapi/tests/devinst.c b/dlls/setupapi/tests/devinst.c
index f1f44af3675..009b94a70ce 100644
--- a/dlls/setupapi/tests/devinst.c
+++ b/dlls/setupapi/tests/devinst.c
@@ -204,7 +204,6 @@ static void testInstallClass(void)
     create_inf_file(tmpfile + 2);
 
     ret = pSetupDiInstallClassA(NULL, NULL, 0, NULL);
-    todo_wine
     ok(!ret && GetLastError() == ERROR_INVALID_PARAMETER,
      "Expected ERROR_INVALID_PARAMETER, got %08x\n", GetLastError());
     ret = pSetupDiInstallClassA(NULL, NULL, DI_NOVCP, NULL);