diff --git a/fpdfsdk/cpdfsdk_interform.cpp b/fpdfsdk/cpdfsdk_interform.cpp
index 03a782b..3b76dca 100644
--- a/fpdfsdk/cpdfsdk_interform.cpp
+++ b/fpdfsdk/cpdfsdk_interform.cpp
@@ -530,7 +530,7 @@
   }
 
   nBufSize = fdfEncodedData.tellp();
-  if (nBufSize == 0)
+  if (nBufSize <= 0)
     return false;
 
   pBuf = FX_Alloc(uint8_t, nBufSize);