diff --git a/lib/preprocessor.cpp b/lib/preprocessor.cpp
index 601618dc2..5acf7a8bf 100644
--- a/lib/preprocessor.cpp
+++ b/lib/preprocessor.cpp
@@ -69,6 +69,41 @@ static unsigned char readChar(std::istream &istr)
     return ch;
 }
 
+// Splits a string that contains the specified separator into substrings
+static std::list<std::string> split(const std::string &s, char separator)
+{
+    std::list<std::string> parts;
+
+    std::string::size_type prevPos = 0;
+    for (std::string::size_type pos = 0; pos < s.length(); ++pos)
+    {
+        if (s[pos] == separator)
+        {
+            if (pos > prevPos)
+                parts.push_back(s.substr(prevPos, pos - prevPos));
+            prevPos = pos + 1;
+        }
+    }
+    if (prevPos < s.length())
+        parts.push_back(s.substr(prevPos));
+
+    return parts;
+}
+
+// Concatenates a list of strings, inserting a separator between parts
+static std::string join(const std::list<std::string> &list, char separator)
+{
+    std::string s;
+    for (std::list<std::string>::const_iterator it = list.begin(); it != list.end(); ++it)
+    {
+        if (!s.empty())
+            s += separator;
+
+        s += *it;
+    }
+    return s;
+}
+
 /** Just read the code into a string. Perform simple cleanup of the code */
 std::string Preprocessor::read(std::istream &istr, const std::string &filename, Settings *settings)
 {
@@ -743,6 +778,7 @@ std::list<std::string> Preprocessor::getcfgs(const std::string &filedata, const
                 deflist.pop_back();
             deflist.push_back(def);
             def = "";
+
             for (std::list<std::string>::const_iterator it = deflist.begin(); it != deflist.end(); ++it)
             {
                 if (*it == "0")
@@ -891,20 +927,24 @@ std::list<std::string> Preprocessor::getcfgs(const std::string &filedata, const
             }
 
             varList.sort();
-            s = "";
-            for (std::list<std::string>::iterator varIter = varList.begin(); varIter != varList.end(); ++varIter)
-            {
-                if (!s.empty())
-                    s += ";";
-
-                s += *varIter;
-            }
+            s = join(varList, ';');
 
             if (!s.empty())
                 *it = s;
         }
     }
 
+    // Convert configurations into a canonical form: B;C;A or C;A;B => A;B;C
+    for (std::list<std::string>::iterator it = ret.begin(); it != ret.end(); ++it)
+    {
+        // Split the configuration into a list of defines
+        std::list<std::string> defs = split(*it, ';');
+
+        // Re-constitute the configuration after sorting the defines
+        defs.sort();
+        *it = join(defs, ';');
+    }
+
     // Remove duplicates from the ret list..
     ret.sort();
     ret.unique();
diff --git a/test/testpreprocessor.cpp b/test/testpreprocessor.cpp
index cb7904182..21013e1d1 100644
--- a/test/testpreprocessor.cpp
+++ b/test/testpreprocessor.cpp
@@ -178,6 +178,8 @@ private:
         // define and then ifdef
         TEST_CASE(define_ifdef);
         TEST_CASE(endfile);
+
+        TEST_CASE(redundant_config);
     }
 
 
@@ -2068,6 +2070,38 @@ private:
         }
     }
 
+    void redundant_config()
+    {
+        const char filedata[] = "int main() {\n"
+                                "#ifdef FOO\n"
+                                "#ifdef BAR\n"
+                                "    std::cout << 1;\n"
+                                "#endif\n"
+                                "#endif\n"
+                                "\n"
+                                "#ifdef BAR\n"
+                                "#ifdef FOO\n"
+                                "    std::cout << 2;\n"
+                                "#endif\n"
+                                "#endif\n"
+                                "}\n";
+
+
+        // Preprocess => actual result..
+        std::istringstream istr(filedata);
+        std::map<std::string, std::string> actual;
+        Preprocessor preprocessor;
+        preprocessor.preprocess(istr, actual, "file.c");
+
+        // Compare results..
+        ASSERT_EQUALS(4U, actual.size());
+        ASSERT(actual.find("") != actual.end());
+        ASSERT(actual.find("BAR") != actual.end());
+        ASSERT(actual.find("FOO") != actual.end());
+        ASSERT(actual.find("BAR;FOO") != actual.end());
+    }
+
+
     void endfile()
     {
         const char filedata[] = "char a[] = \"#endfile\";\n"
diff --git a/test/testsuite.cpp b/test/testsuite.cpp
index a6f5c8779..484e7aa67 100644
--- a/test/testsuite.cpp
+++ b/test/testsuite.cpp
@@ -105,6 +105,15 @@ static std::string writestr(const std::string &str)
     return ostr.str();
 }
 
+void TestFixture::assert(const char *filename, int linenr, bool condition)
+{
+    if (!condition)
+    {
+        ++fails_counter;
+        errmsg << "Assertion failed in " << filename << " at line " << linenr << std::endl;
+    }
+}
+
 void TestFixture::assertEquals(const char *filename, int linenr, const std::string &expected, const std::string &actual)
 {
     if (expected != actual)
diff --git a/test/testsuite.h b/test/testsuite.h
index 5a2ab242c..785e9fa37 100644
--- a/test/testsuite.h
+++ b/test/testsuite.h
@@ -41,6 +41,8 @@ protected:
 
     bool runTest(const char testname[]);
 
+    void assert(const char *filename, int linenr, bool condition);
+
     void assertEquals(const char *filename, int linenr, const std::string &expected, const std::string &actual);
 
     // the vars expected and actual need to be of type double, in order to avoid overflow of unsigned int
@@ -66,6 +68,7 @@ public:
 
 
 #define TEST_CASE( NAME )  if ( runTest(#NAME) ) NAME ();
+#define ASSERT( CONDITION )  assert(__FILE__, __LINE__, CONDITION)
 #define ASSERT_EQUALS( EXPECTED , ACTUAL )  assertEquals(__FILE__, __LINE__, EXPECTED, ACTUAL)
 #define ASSERT_THROW( CMD, EXCEPTION ) try { CMD ; assertThrowFail(__FILE__, __LINE__); } catch (EXCEPTION &) { } catch (...) { assertThrowFail(__FILE__, __LINE__); }
 #define TODO_ASSERT_EQUALS( EXPECTED , ACTUAL ) todoAssertEquals(__FILE__, __LINE__, EXPECTED, ACTUAL)