diff --git a/goo/gfile.cc b/goo/gfile.cc
index fe05de67..be75c5a6 100644
--- a/goo/gfile.cc
+++ b/goo/gfile.cc
@@ -670,6 +670,22 @@ GooFile* GooFile::open(const GooString *fileName) {
   return fd < 0 ? NULL : new GooFile(fd);
 }
 
+GooFile::GooFile(int fdA)
+ : fd(fdA)
+{
+    struct stat statbuf;
+    fstat(fd, &statbuf);
+    modifiedTimeOnOpen = statbuf.st_mtim;
+}
+
+bool GooFile::modificationTimeChangedSinceOpen() const
+{
+    struct stat statbuf;
+    fstat(fd, &statbuf);
+
+    return modifiedTimeOnOpen.tv_sec != statbuf.st_mtim.tv_sec || modifiedTimeOnOpen.tv_nsec != statbuf.st_mtim.tv_nsec;
+}
+
 #endif // _WIN32
 
 //------------------------------------------------------------------------
diff --git a/goo/gfile.h b/goo/gfile.h
index 805e5232..233c4829 100644
--- a/goo/gfile.h
+++ b/goo/gfile.h
@@ -145,16 +145,22 @@ public:
   static GooFile *open(const wchar_t *fileName);
   
   ~GooFile() { CloseHandle(handle); }
+
+  // Asuming than on windows you can't change files that are already open
+  bool modificationTimeChangedSinceOpen() const { return false; };
   
 private:
   GooFile(HANDLE handleA): handle(handleA) {}
   HANDLE handle;
 #else
   ~GooFile() { close(fd); }
+
+  bool modificationTimeChangedSinceOpen() const;
     
 private:
-  GooFile(int fdA) : fd(fdA) {}
+  GooFile(int fdA);
   int fd;
+  struct timespec modifiedTimeOnOpen;
 #endif // _WIN32
 };
 
diff --git a/poppler/ErrorCodes.h b/poppler/ErrorCodes.h
index b28528df..216412f6 100644
--- a/poppler/ErrorCodes.h
+++ b/poppler/ErrorCodes.h
@@ -33,4 +33,6 @@
 
 #define errFileIO          10   // file I/O error
 
+#define errFileChangedSinceOpen 11   // file has changed since opening and save can't be done
+
 #endif
diff --git a/poppler/PDFDoc.cc b/poppler/PDFDoc.cc
index 147d1f45..3fcc18fe 100644
--- a/poppler/PDFDoc.cc
+++ b/poppler/PDFDoc.cc
@@ -728,6 +728,11 @@ int PDFDoc::savePageAs(GooString *name, int pageNo)
   FILE *f;
   OutStream *outStr;
   XRef *yRef, *countRef;
+
+  if (file && file->modificationTimeChangedSinceOpen())
+    return errFileChangedSinceOpen;
+
+
   int rootNum = getXRef()->getNumObjects() + 1;
 
   // Make sure that special flags are set, because we are going to read
@@ -899,6 +904,9 @@ int PDFDoc::saveAs(GooString *name, PDFWriteMode mode) {
 }
 
 int PDFDoc::saveAs(OutStream *outStr, PDFWriteMode mode) {
+  if (file && file->modificationTimeChangedSinceOpen())
+    return errFileChangedSinceOpen;
+
   if (!xref->isModified() && mode == writeStandard) {
     // simply copy the original file
     saveWithoutChangesAs (outStr);
@@ -932,6 +940,9 @@ int PDFDoc::saveWithoutChangesAs(GooString *name) {
 
 int PDFDoc::saveWithoutChangesAs(OutStream *outStr) {
   int c;
+
+  if (file && file->modificationTimeChangedSinceOpen())
+    return errFileChangedSinceOpen;
   
   BaseStream *copyStr = str->copy();
   copyStr->reset();