diff --git a/src/add-ons/print/drivers/gutenprint/GPArray.cpp b/src/add-ons/print/drivers/gutenprint/GPArray.cpp
index aab29cbff9..e44771bd51 100644
--- a/src/add-ons/print/drivers/gutenprint/GPArray.cpp
+++ b/src/add-ons/print/drivers/gutenprint/GPArray.cpp
@@ -32,7 +32,7 @@ template<typename TYPE>
 void
 GPArray<TYPE>::SetSize(int size)
 {
-	ASSERT(fSize == NULL);
+	ASSERT(fSize == 0);
 	fArray = new PointerType[size];
 	if (fArray == NULL)
 		return;