diff --git a/src/SrmRideFile.cpp b/src/SrmRideFile.cpp
index 4a02becbc..160e39fb2 100644
--- a/src/SrmRideFile.cpp
+++ b/src/SrmRideFile.cpp
@@ -207,6 +207,7 @@ RideFile *SrmFileReader::openRideFile(QFile &file, QStringList &errorStrings, QL
     }
 
     blockhdr *blockhdrs = new blockhdr[blockcnt+1];
+    int blockchunkcnt = 0;
     for (int i = 0; i < blockcnt; ++i) {
         // In the .srm files generated by Rainer Clasen's srmcmd,
         // hsecsincemidn is a *signed* 32-bit integer.  I haven't seen a
@@ -217,6 +218,7 @@ RideFile *SrmFileReader::openRideFile(QFile &file, QStringList &errorStrings, QL
         blockhdrs[i].chunkcnt = readShort(in);
         blockhdrs[i].dt = QDateTime(date);
         blockhdrs[i].dt = blockhdrs[i].dt.addMSecs(hsecsincemidn * 10);
+        blockchunkcnt += blockhdrs[i].chunkcnt;
     }
 
     // fail early to tell devs whats wrong with file
@@ -247,6 +249,13 @@ RideFile *SrmFileReader::openRideFile(QFile &file, QStringList &errorStrings, QL
         blockhdrs[0].dt = QDateTime(date);
     }
 
+    // datacnt might overflow at 64k - so, use sum from blocks, instead
+    if( datacnt > blockchunkcnt ){
+        blockchunkcnt = datacnt;
+        errorStrings << QString("inconsistent chunk count total=%1, blocks=%2")
+            .arg(datacnt)
+            .arg(blockchunkcnt);
+    }
 
     int blknum = 0, blkidx = 0, mrknum = 0, interval = 0;
     double km = 0.0, secs = 0.0;
@@ -254,7 +263,7 @@ RideFile *SrmFileReader::openRideFile(QFile &file, QStringList &errorStrings, QL
     if (markercnt > 0)
         mrknum = 1;
 
-    for (int i = 0; i < datacnt; ++i) {
+    for (int i = 0; i < blockchunkcnt; ++i) {
         int cad, hr, watts;
         double kph, alt;
         double temp=-255;
@@ -268,8 +277,7 @@ RideFile *SrmFileReader::openRideFile(QFile &file, QStringList &errorStrings, QL
             watts = (ps[1] & 0x0f) | (ps[2] << 0x4);
             alt = 0.0;
         }
-        else {
-            assert(version == 7);
+        else if (version == 7 ){
             watts = readShort(in);
             cad = readByte(in);
             hr = readByte(in);
@@ -280,6 +288,16 @@ RideFile *SrmFileReader::openRideFile(QFile &file, QStringList &errorStrings, QL
             alt = readSignedLong(in);
             temp = 0.1 * readSignedShort(in);
         }
+        else {
+            errorStrings << QString("unsupported SRM file version: %1")
+                .arg( version );
+            return NULL;
+        }
+
+        if( in.status() != QDataStream::Ok ){
+            errorStrings << QString("premature end of file" );
+            break;
+        }
 
         if (i == 0) {
             result->setStartTime(blockhdrs[blknum].dt);