diff --git a/demo/common.h b/demo/common.h
index 0a2f2d8..30a302c 100644
--- a/demo/common.h
+++ b/demo/common.h
@@ -45,6 +45,7 @@ void write(const char *filename,
         fclose(out);
         if (written == 0) {
             perror("write error");
+            exit(4);
         }
     }
 }
@@ -61,6 +62,7 @@ void append(const char *filename, const char *t, unsigned size) {
         fclose(out);
         if (written == 0) {
             perror("write error");
+            exit(4);
         }
     }
 }
diff --git a/demo/extractmesh.c b/demo/extractmesh.c
index 62b89de..71dbe23 100644
--- a/demo/extractmesh.c
+++ b/demo/extractmesh.c
@@ -25,22 +25,22 @@ void writemesh(const struct MeshHeader *mh,
 
     // batch data the same treatment.
     struct BatchData * newBatches = malloc(newmh.numBatch * sizeof(struct BatchData));
-    uint64_t previousBatch = 0;
+    uint64_t endOfPrevious = 0;
     for (int i = 0; i < newmh.numBatch; i++) {
       newBatches[i] = (m -> b) -> bd[i];
       unsigned int nVertices = m -> b -> bd[i].numVertex;
-      if (previousBatch == 0) {
+      if (endOfPrevious == 0) {
         newBatches[i].offsetPositions = newmh.offsetBatches + ( newmh.numBatch * sizeof(struct BatchData));
       }
       else {
-        newBatches[i].offsetPositions = previousBatch;
+        newBatches[i].offsetPositions = endOfPrevious;
       }
       newBatches[i].offsetNormals     = newBatches[i].offsetPositions   + (sizeof(struct Coordinate)  * nVertices);
       newBatches[i].offsetUVs         = newBatches[i].offsetNormals     + (sizeof(struct Coordinate)  * nVertices);
       newBatches[i].offsetBoneIndexes = newBatches[i].offsetUVs         + (sizeof(struct UVs)         * nVertices);
       newBatches[i].offsetBoneWeights = newBatches[i].offsetBoneIndexes + (sizeof(struct BoneIndexes) * nVertices);
       append(fn, (char*)(&newBatches[i]), sizeof(struct BatchData));
-      previousBatch                   = newBatches[i].offsetBoneWeights + (sizeof(struct BoneWeights) * nVertices);;
+      endOfPrevious                   = newBatches[i].offsetBoneWeights + (sizeof(struct BoneWeights) * nVertices);;
     }
 
     for (int i = 0; i < newmh.numBatch; i++) {
@@ -57,8 +57,8 @@ void writemesh(const struct MeshHeader *mh,
 }
 
 void extractmeshes(const char *filedata,
-                   unsigned int filesize,
-                   const char *filename) {
+                   const char *filename,
+                   unsigned int filesize) {
     if (filedata == NULL || filesize <= 0) {
         return;
     }
@@ -71,7 +71,7 @@ void extractmeshes(const char *filedata,
         DEVIL1GEO.getmeshheader(&mh, i, filedata);
         m.b = (struct Batch*)malloc(sizeof(struct Batch) * (mh -> numBatch));
         if (m.b != NULL) {
-            DEVIL1GEO.getmesh(&m, i, filedata);
+            DEVIL1GEO.getmesh(&m, i, filedata, filesize);
             writemesh(mh, &m, filename, i);
             free(m.b);
         }
@@ -83,7 +83,7 @@ int main(int argc, char ** argv) {
     char *f = argv[1];
     unsigned int bufsize = 0;
     char *buffer         = loadfile(f, &bufsize);
-    extractmeshes(buffer, bufsize, f);
+    extractmeshes(buffer, f, bufsize);
     free(buffer);
     return 0;
 }
diff --git a/include/devil1geo.h b/include/devil1geo.h
index 9755435..7b6b3d2 100644
--- a/include/devil1geo.h
+++ b/include/devil1geo.h
@@ -99,7 +99,8 @@ typedef struct {
 // input: pointer to struct, order, file data
     bool (* const getmesh)        (struct Mesh*, 
                                    unsigned int i, 
-                                   const char*);
+                                   const char*,
+                                   unsigned int filesize);
 } fn_devil1geo;
 extern fn_devil1geo const DEVIL1GEO;
 
diff --git a/src/devil1geo.c b/src/devil1geo.c
index 25f5d88..b329072 100644
--- a/src/devil1geo.c
+++ b/src/devil1geo.c
@@ -14,7 +14,7 @@ static bool getmeshheader(struct MeshHeader**, unsigned int i, const char * cons
 
 static bool getmeshbatch(struct Batch*, unsigned int offset, const char * const);
 
-static bool getmesh(struct Mesh*, unsigned int i, const char*);
+static bool getmesh(struct Mesh*, unsigned int i, const char*, unsigned int filesize);
 
 fn_devil1geo const DEVIL1GEO = {printgheader,
                                 printmeshheader,
@@ -115,7 +115,8 @@ static bool getmeshbatch(struct Batch *b,
 // assume client has allocated memory for mesh
 static bool getmesh(struct Mesh *m,
              unsigned int i,
-             const char * const filedata) {        
+             const char * const filedata,
+             unsigned int filesize) {
     bool done = false;
     if (m == NULL || filedata == NULL || m -> b == NULL) {
         return done;
@@ -127,6 +128,9 @@ static bool getmesh(struct Mesh *m,
         struct Batch b;
         for (j = 0; j < mh -> numBatch; j++) {
             unsigned int offset = mh->offsetBatches + j * sizeof(struct BatchData);
+            if (offset > filesize) {
+              return done;
+            }
             getmeshbatch(&b, offset, filedata);
 //            printmeshbatch(&b);
             m -> b[j] = b;
diff --git a/src/devil1pld.c b/src/devil1pld.c
index 7717d98..61ab8ea 100644
--- a/src/devil1pld.c
+++ b/src/devil1pld.c
@@ -14,7 +14,9 @@ static bool getpldh(struct PldHeader *ph, const char *filedata) {
     if (ph != NULL && filedata != NULL) {
         ph -> numOffset = (int32_t)filedata[0];
         ph -> offsets   = (uint32_t*)(filedata + sizeof(int32_t));
-        good = true;
+        if ( ph->numOffset > 0 ) {
+          good = true;
+        }
     }
     return good;
 }
diff --git a/src/devil1tex.c b/src/devil1tex.c
index b27fc81..5b4d8dd 100644
--- a/src/devil1tex.c
+++ b/src/devil1tex.c
@@ -63,7 +63,7 @@ static bool gettexdescriptor(struct TextureBatchDescriptor **descriptor,
     bool done = false;
     unsigned int offset = sizeof(struct TexturePack);
     offset += sizeof(struct TextureBatchDescriptor) * i;
-    if (filedata != NULL) {
+    if (filedata != NULL && offset <= filesize) {
         *descriptor = (struct TextureBatchDescriptor*)(filedata + offset);
         done = true;
     }