diff --git a/source/emunand9.c b/source/emunand9.c
index 44e830b..07eba74 100644
--- a/source/emunand9.c
+++ b/source/emunand9.c
@@ -398,7 +398,7 @@ u32 InjectNand(u32 param)
             FileClose();
             return 1;
         }
-        if (IS_NAND_HEADER(buffer)) {
+        if (!IS_NAND_HEADER(buffer)) {
             FileClose();
             Debug("Not a proper NAND dump!");
             return 1;