diff --git a/ApplicationCode/Commands/ViewLink/RicLinkVisibleViewsFeatureUi.cpp b/ApplicationCode/Commands/ViewLink/RicLinkVisibleViewsFeatureUi.cpp
index 0bb5c58f2b..424bc34ae6 100644
--- a/ApplicationCode/Commands/ViewLink/RicLinkVisibleViewsFeatureUi.cpp
+++ b/ApplicationCode/Commands/ViewLink/RicLinkVisibleViewsFeatureUi.cpp
@@ -79,7 +79,7 @@ QList<caf::PdmOptionItemInfo> RicLinkVisibleViewsFeatureUi::calculateValueOption
 
     if (fieldNeedingOptions == &m_masterView)
     {
-        for (int i = 0; i < m_allViews.size(); i++)
+        for (size_t i = 0; i < m_allViews.size(); i++)
         {
             RimCase* rimCase = NULL;
             m_allViews[i]->firstAnchestorOrThisOfType(rimCase);
diff --git a/ApplicationCode/GeoMech/GeoMechVisualization/RivGeoMechVizLogic.cpp b/ApplicationCode/GeoMech/GeoMechVisualization/RivGeoMechVizLogic.cpp
index d996ac188f..e7d9f59231 100644
--- a/ApplicationCode/GeoMech/GeoMechVisualization/RivGeoMechVizLogic.cpp
+++ b/ApplicationCode/GeoMech/GeoMechVisualization/RivGeoMechVizLogic.cpp
@@ -246,7 +246,7 @@ void RivGeoMechVizLogic::calculateCurrentTotalCellVisibility(cvf::UByteArray* to
     if (gridCount == 0) return;
 
     RigFemPart* part = m_geomechView->geoMechCase()->geoMechData()->femParts()->part(0);
-    size_t elmCount = part->elementCount();
+    int elmCount = part->elementCount();
 
     totalVisibility->resize(elmCount);
     totalVisibility->setAll(false);
diff --git a/ApplicationCode/ProjectDataModel/ProjectDataModel_UnitTests/RimWellLogExtractionCurveImpl-Test.cpp b/ApplicationCode/ProjectDataModel/ProjectDataModel_UnitTests/RimWellLogExtractionCurveImpl-Test.cpp
index 53b0b86b32..1c9932b9a8 100644
--- a/ApplicationCode/ProjectDataModel/ProjectDataModel_UnitTests/RimWellLogExtractionCurveImpl-Test.cpp
+++ b/ApplicationCode/ProjectDataModel/ProjectDataModel_UnitTests/RimWellLogExtractionCurveImpl-Test.cpp
@@ -21,9 +21,9 @@ TEST(RimWellLogExtractionCurveImplTest, StripOffInvalidValAtEndsOfVector)
     std::vector< std::pair<size_t, size_t> > valuesIntervals;
     RimWellLogCurveImpl::calculateIntervalsOfValidValues(values, valuesIntervals);
 
-    EXPECT_EQ(1, valuesIntervals.size());
-    EXPECT_EQ(2, valuesIntervals[0].first);
-    EXPECT_EQ(4, valuesIntervals[0].second);
+    EXPECT_EQ(1, static_cast<int>(valuesIntervals.size()));
+    EXPECT_EQ(2, static_cast<int>(valuesIntervals[0].first));
+    EXPECT_EQ(4, static_cast<int>(valuesIntervals[0].second));
 }
 
 
diff --git a/ApplicationCode/ProjectDataModel/RimWellLogCurveImpl.cpp b/ApplicationCode/ProjectDataModel/RimWellLogCurveImpl.cpp
index 5ce8c01c90..3bea08b79a 100644
--- a/ApplicationCode/ProjectDataModel/RimWellLogCurveImpl.cpp
+++ b/ApplicationCode/ProjectDataModel/RimWellLogCurveImpl.cpp
@@ -83,7 +83,7 @@ void RimWellLogCurveImpl::calculateIntervalsOfValidValues(const std::vector<doub
         vIdx++;
     }
 
-    if (startIdx >= 0 && startIdx < valueCount)
+    if (startIdx >= 0 && startIdx < ((int)valueCount))
     {
         intervals.push_back(std::make_pair(startIdx, valueCount - 1));
     }
diff --git a/Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmReferenceHelper.cpp b/Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmReferenceHelper.cpp
index 888a0ad9ca..1427e59c1a 100644
--- a/Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmReferenceHelper.cpp
+++ b/Fwk/AppFwk/cafProjectDataModel/cafPdmCore/cafPdmReferenceHelper.cpp
@@ -231,7 +231,7 @@ PdmObjectHandle* PdmReferenceHelper::objectFromReferenceStringList(PdmObjectHand
             return NULL;
         }
 
-        if (index > childObjects.size() - 1)
+        if (index < 0 || index > ((int)childObjects.size()) - 1)
         {
             return NULL;
         }
diff --git a/ThirdParty/NRLib/nrlib/well/well.hpp b/ThirdParty/NRLib/nrlib/well/well.hpp
index db033724f8..2f1920d0c5 100644
--- a/ThirdParty/NRLib/nrlib/well/well.hpp
+++ b/ThirdParty/NRLib/nrlib/well/well.hpp
@@ -155,7 +155,7 @@ namespace NRLib {
 
     virtual const std::map<int, std::string> GetDiscNames(const std::string& log_name) const;
 
-    const unsigned int GetNumberOfNonMissingData()  const {return n_data_nonmissing_ ;}
+    unsigned int GetNumberOfNonMissingData()  const {return n_data_nonmissing_ ;}
 
     void SetUseForBackgroundTrend(int use_for_background_trend)         { use_for_background_trend_     = use_for_background_trend     ;}
     void SetUseForFiltering(int use_for_filtering)                      { use_for_filtering_            = use_for_filtering            ;}