diff --git a/src/providers/spatialite/qgsspatialiteprovider.cpp b/src/providers/spatialite/qgsspatialiteprovider.cpp
index ed0a47c72719..ffb488ee1f3c 100644
--- a/src/providers/spatialite/qgsspatialiteprovider.cpp
+++ b/src/providers/spatialite/qgsspatialiteprovider.cpp
@@ -3696,7 +3696,7 @@ bool QgsSpatiaLiteProvider::addFeatures( QgsFeatureList & flist )
         {
           // some unexpected error occurred
           const char *err = sqlite3_errmsg( sqliteHandle );
-          errMsg = ( char * ) sqlite3_malloc( strlen( err ) + 1 );
+          errMsg = ( char * ) sqlite3_malloc(( int ) strlen( err ) + 1 );
           strcpy( errMsg, err );
           break;
         }
@@ -3771,7 +3771,7 @@ bool QgsSpatiaLiteProvider::deleteFeatures( const QgsFeatureIds &id )
     {
       // some unexpected error occurred
       const char *err = sqlite3_errmsg( sqliteHandle );
-      errMsg = ( char * ) sqlite3_malloc( strlen( err ) + 1 );
+      errMsg = ( char * ) sqlite3_malloc(( int ) strlen( err ) + 1 );
       strcpy( errMsg, err );
       goto abort;
     }
@@ -4031,7 +4031,7 @@ bool QgsSpatiaLiteProvider::changeGeometryValues( QgsGeometryMap & geometry_map
     {
       // some unexpected error occurred
       const char *err = sqlite3_errmsg( sqliteHandle );
-      errMsg = ( char * ) sqlite3_malloc( strlen( err ) + 1 );
+      errMsg = ( char * ) sqlite3_malloc(( int ) strlen( err ) + 1 );
       strcpy( errMsg, err );
       goto abort;
     }
diff --git a/src/providers/virtual/qgsvirtuallayersqlitemodule.cpp b/src/providers/virtual/qgsvirtuallayersqlitemodule.cpp
index 80b4fbcec054..8c17dc3c2c27 100644
--- a/src/providers/virtual/qgsvirtuallayersqlitemodule.cpp
+++ b/src/providers/virtual/qgsvirtuallayersqlitemodule.cpp
@@ -306,8 +306,8 @@ int vtable_create_connect( sqlite3* sql, void* aux, int argc, const char* const*
   Q_UNUSED( aux );
   Q_UNUSED( is_created );
 
-#define RETURN_CSTR_ERROR(err) if (out_err) {size_t s = strlen(err); *out_err=(char*)sqlite3_malloc(s+1); strncpy(*out_err, err, s);}
-#define RETURN_CPPSTR_ERROR(err) if (out_err) {*out_err=(char*)sqlite3_malloc(err.size()+1); strncpy(*out_err, err.c_str(), err.size());}
+#define RETURN_CSTR_ERROR(err) if (out_err) {size_t s = strlen(err); *out_err=(char*)sqlite3_malloc( (int) s+1); strncpy(*out_err, err, s);}
+#define RETURN_CPPSTR_ERROR(err) if (out_err) {*out_err=(char*)sqlite3_malloc( (int) err.size()+1); strncpy(*out_err, err.c_str(), err.size());}
 
   if ( argc < 4 )
   {