diff --git a/src/blackmisc/collection.h b/src/blackmisc/collection.h
index 2fe56dc2e..59253850a 100644
--- a/src/blackmisc/collection.h
+++ b/src/blackmisc/collection.h
@@ -172,6 +172,20 @@ namespace BlackMisc
          */
         iterator erase(iterator it1, iterator it2) { Q_ASSERT(pimpl()); return pimpl()->erase(it1, it2); }
 
+        /*!
+         * \brief Efficient find method using the find of the implementation container. Typically O(log n).
+         * \return An iterator to the position of the found element, or the end iterator if not found.
+         * \pre The sequence must be initialized.
+         */
+        iterator find(const T &value) { Q_ASSERT(pimpl()); return pimpl()->find(value); }
+
+        /*!
+         * \brief Efficient find method using the find of the implementation container. Typically O(log n).
+         * \return An iterator to the position of the found element, or the end iterator if not found.
+         * \pre The sequence must be initialized.
+         */
+        const_iterator find(const T &value) const { Q_ASSERT(pimpl()); return pimpl()->find(value); }
+
         /*!
          * \brief Test for equality.
          * \todo Improve inefficient implementation.
@@ -203,16 +217,9 @@ namespace BlackMisc
             virtual iterator insert(const T &value) = 0;
             virtual iterator erase(iterator pos) = 0;
             virtual iterator erase(iterator it1, iterator it2) = 0;
+            virtual iterator find(const T &value) = 0;
+            virtual const_iterator find(const T &value) const = 0;
             virtual bool operator ==(const PimplBase &other) const = 0;
-        protected:
-            // using SFINAE to choose whether to implement insert() in terms of either push_back() or insert(), depending on which is available
-            // https://groups.google.com/forum/#!original/comp.lang.c++.moderated/T3x6lvmvvkQ/mfY5VTDJ--UJ
-            class yes { char x; }; class no { yes x[2]; }; template <class X, X V> struct typecheck {};
-            struct base { void push_back(); }; template <class C> struct derived : public C, public base {};
-            static yes hasPushHelper(...); template <class D> static no hasPushHelper(D *, typecheck<void (base::*)(), &D::push_back> * = 0);
-            template <class C> struct hasPush : public std::integral_constant<bool, sizeof(hasPushHelper((derived<C>*)0)) == sizeof(yes)> {};
-            template <class C> static iterator insertImpl(typename std::enable_if< hasPush<C>::value, C>::type &c, const T &value) { c.push_back(value); return iterator::fromImpl(c.end() - 1); }
-            template <class C> static iterator insertImpl(typename std::enable_if < !hasPush<C>::value, C >::type &c, const T &value) { return iterator::fromImpl(c.insert(value)); }
         };
 
         template <class C> class Pimpl : public PimplBase
@@ -231,13 +238,18 @@ namespace BlackMisc
             size_type size() const { return m_impl.size(); }
             bool empty() const { return m_impl.empty(); }
             void clear() { m_impl.clear(); }
-            iterator insert(const T &value) { return PimplBase::insertImpl<C>(m_impl, value); }
+            iterator insert(const T &value) { return iterator::fromImpl(insertHelper(m_impl.insert(value))); }
             iterator erase(iterator pos) { return iterator::fromImpl(m_impl.erase(*static_cast<const typename C::iterator *>(pos.getImpl()))); }
             //iterator erase(iterator it1, iterator it2) { return iterator::fromImpl(m_impl.erase(*static_cast<const typename C::iterator *>(it1.getImpl()), *static_cast<const typename C::iterator*>(it2.getImpl()))); }
             iterator erase(iterator it1, iterator it2) { while (it1 != it2) { it1 = iterator::fromImpl(m_impl.erase(*static_cast<const typename C::iterator *>(it1.getImpl()))); } return it1; }
+            iterator find(const T &value) { return iterator::fromImpl(m_impl.find(value)); }
+            const_iterator find(const T &value) const { return const_iterator::fromImpl(m_impl.find(value)); }
             bool operator ==(const PimplBase &other) const { Pimpl copy = C(); for (auto i = other.cbegin(); i != other.cend(); ++i) copy.insert(*i); return m_impl == copy.m_impl; }
         private:
             C m_impl;
+            // insertHelper: QSet::insert returns an iterator, but std::set::insert returns a std::pair<interator, bool>
+            template <class I> static I insertHelper(I i) { return i; }
+            template <class I> static I insertHelper(std::pair<I, bool> p) { return p.first; }
         };
 
         typedef QScopedPointer<PimplBase> PimplPtr;
diff --git a/src/blackmisc/containerbase.h b/src/blackmisc/containerbase.h
index 7586938eb..6873b33ba 100644
--- a/src/blackmisc/containerbase.h
+++ b/src/blackmisc/containerbase.h
@@ -95,11 +95,11 @@ namespace BlackMisc
         }
 
         /*!
-         * \brief Return true if there is an element equal to given object
+         * \brief Return true if there is an element equal to given object. Uses the most efficient implementation available.
          */
         bool contains(const T &object) const
         {
-            return std::find(derived().begin(), derived().end(), object) != derived().end();
+            return derived().find(object) != derived().end();
         }
 
         /*!
diff --git a/src/blackmisc/iterator.h b/src/blackmisc/iterator.h
index 56b2c9d2d..06a96e27b 100644
--- a/src/blackmisc/iterator.h
+++ b/src/blackmisc/iterator.h
@@ -152,7 +152,7 @@ namespace BlackMisc
                 virtual PimplBase *clone() const { return new Pimpl(*this); }
                 virtual const_reference operator *() const { return *m_impl; }
                 virtual void operator ++() { ++m_impl; }
-                virtual void operator +=(difference_type n) { m_impl += n; }
+                virtual void operator +=(difference_type n) { std::advance(m_impl, n); }
                 virtual bool operator ==(const PimplBase &other) const { return m_impl == static_cast<const Pimpl&>(other).m_impl; }
                 virtual void *impl() { return &m_impl; }
             private:
diff --git a/src/blackmisc/sequence.h b/src/blackmisc/sequence.h
index 500fb4343..1b2a09e45 100644
--- a/src/blackmisc/sequence.h
+++ b/src/blackmisc/sequence.h
@@ -219,6 +219,11 @@ namespace BlackMisc
          */
         iterator erase(iterator it1, iterator it2) { Q_ASSERT(pimpl()); return pimpl()->erase(it1, it2); }
 
+        /*!
+         * \brief Return an iterator to the first element equal to the given object, or the end iterator if not found. O(n).
+         */
+        iterator find(const T &object) const { return std::find(begin(), end(), object); }
+
         /*!
          * \brief Modify by applying a value map to each element for which a given predicate returns true.
          */
diff --git a/tests/blackmisc/testcontainers.cpp b/tests/blackmisc/testcontainers.cpp
index fbd73612c..b4815cbc0 100644
--- a/tests/blackmisc/testcontainers.cpp
+++ b/tests/blackmisc/testcontainers.cpp
@@ -7,8 +7,10 @@
 #include "blackmisc/collection.h"
 #include "blackmisc/sequence.h"
 #include <QList>
-#include <QString>
+#include <QVector>
+#include <QSet>
 #include <vector>
+#include <set>
 
 using namespace BlackMisc;
 
@@ -19,9 +21,9 @@ namespace BlackMiscTest
     {
         CCollection<int> c1;
         QVERIFY2(c1.empty(), "Uninitialized collection is empty");
-        auto c2 = CCollection<int>::fromImpl(QList<int>());
+        auto c2 = CCollection<int>::fromImpl(QSet<int>());
         QVERIFY2(c1 == c2, "Uninitialized and empty collections are equal");
-        c1.changeImpl(std::vector<int>());
+        c1.changeImpl(std::set<int>());
         QVERIFY2(c1 == c2, "Two empty collections are equal");
         c1.insert(1);
         QVERIFY2(c1 != c2, "Different collections are not equal");