diff --git a/apps/float_pair_store.cpp b/apps/float_pair_store.cpp
index 845d91a85..10dc97754 100644
--- a/apps/float_pair_store.cpp
+++ b/apps/float_pair_store.cpp
@@ -2,6 +2,7 @@
 #include <math.h>
 #include <assert.h>
 #include <stddef.h>
+#include <ion.h>
 
 FloatPairStore::FloatPairStore() :
   m_numberOfPairs(0)
@@ -58,8 +59,7 @@ float FloatPairStore::sumOfColumn(int i) {
 uint32_t FloatPairStore::storeChecksum() {
   size_t dataLengthInBytes = m_numberOfPairs*2*sizeof(float);
   assert((dataLengthInBytes & 0x3) == 0); // Assert that dataLengthInBytes is a multiple of 4
-  //return Ion::crc32((uint32_t *)m_data, dataLengthInBytes>>2);
-  return sumOfColumn(0)+sumOfColumn(1);
+  return Ion::crc32((uint32_t *)m_data, dataLengthInBytes>>2);
 }
 
 float FloatPairStore::defaultValue(int i) {
diff --git a/apps/graph/function_store.cpp b/apps/graph/function_store.cpp
index 42c4d7971..0592f211e 100644
--- a/apps/graph/function_store.cpp
+++ b/apps/graph/function_store.cpp
@@ -3,6 +3,7 @@ extern "C" {
 #include <assert.h>
 }
 #include <stddef.h>
+#include <ion.h>
 
 namespace Graph {
 
@@ -19,8 +20,7 @@ FunctionStore::FunctionStore() :
 uint32_t FunctionStore::storeChecksum() {
   size_t dataLengthInBytes = m_numberOfFunctions*sizeof(Function);
   assert((dataLengthInBytes & 0x3) == 0); // Assert that dataLengthInBytes is a multiple of 4
-  //return Ion::crc32((uint32_t *)m_functions, dataLengthInBytes>>2);
-  return m_numberOfFunctions;
+  return Ion::crc32((uint32_t *)m_functions, dataLengthInBytes>>2);
 }
 
 Function * FunctionStore::functionAtIndex(int i) {
diff --git a/apps/interactive_curve_view_range.cpp b/apps/interactive_curve_view_range.cpp
index 9403cd215..ce97048e7 100644
--- a/apps/interactive_curve_view_range.cpp
+++ b/apps/interactive_curve_view_range.cpp
@@ -25,8 +25,7 @@ uint32_t InteractiveCurveViewRange::rangeChecksum() {
   float data[5] = {m_xMin, m_xMax, m_yMin, m_yMax, m_yAuto ? 1.0f : 0.0f};
   size_t dataLengthInBytes = 5*sizeof(float);
   assert((dataLengthInBytes & 0x3) == 0); // Assert that dataLengthInBytes is a multiple of 4
-  //return Ion::crc32((uint32_t *)data, dataLengthInBytes>>2);
-  return m_xMin+ m_xMax+ m_yMin+ m_yMax+ m_yAuto;
+  return Ion::crc32((uint32_t *)data, dataLengthInBytes>>2);
 }
 
 float InteractiveCurveViewRange::xMin() {
diff --git a/apps/statistics/store.cpp b/apps/statistics/store.cpp
index 36d78b90b..a6f2d734c 100644
--- a/apps/statistics/store.cpp
+++ b/apps/statistics/store.cpp
@@ -3,6 +3,7 @@
 #include <float.h>
 #include <math.h>
 #include <string.h>
+#include <ion.h>
 
 namespace Statistics {
 
@@ -18,8 +19,7 @@ uint32_t Store::barChecksum() {
   float data[2] = {m_barWidth, m_firstDrawnBarAbscissa};
   size_t dataLengthInBytes = 2*sizeof(float);
   assert((dataLengthInBytes & 0x3) == 0); // Assert that dataLengthInBytes is a multiple of 4
-  //return Ion::crc32((uint32_t *)data, dataLengthInBytes>>2);
-  return m_barWidth + m_firstDrawnBarAbscissa;
+  return Ion::crc32((uint32_t *)data, dataLengthInBytes>>2);
 }
 
 /* Histogram bars */