diff --git a/lib/preprocessor.cpp b/lib/preprocessor.cpp
index 2bebef65b..6c37e43a1 100644
--- a/lib/preprocessor.cpp
+++ b/lib/preprocessor.cpp
@@ -1422,7 +1422,7 @@ std::string Preprocessor::getcode(const std::string &filedata, const std::string
     std::stack<unsigned int> lineNumbers;
     std::istringstream istr(filedata);
     std::string line;
-    while (getline(istr, line)) {
+    while (std::getline(istr, line)) {
         ++lineno;
 
         if (line.compare(0, 11, "#pragma asm") == 0) {
@@ -1496,6 +1496,11 @@ std::string Preprocessor::getcode(const std::string &filedata, const std::string
             }
         }
 
+        else if (line.compare(0, 7, "#undef ") == 0) {
+            const std::string name(line.substr(7));
+            cfgmap.erase(name);
+        }
+
         else if (!emptymatch && line.compare(0, 7, "#elif !") == 0) {
             if (matched_ifdef.back()) {
                 matching_ifdef.back() = false;
diff --git a/test/testpreprocessor.cpp b/test/testpreprocessor.cpp
index 4aaa837ed..41842c189 100644
--- a/test/testpreprocessor.cpp
+++ b/test/testpreprocessor.cpp
@@ -205,6 +205,7 @@ private:
         TEST_CASE(define_ifdef);
         TEST_CASE(define_ifndef1);
         TEST_CASE(define_ifndef2);
+        TEST_CASE(undef_ifdef);
         TEST_CASE(endfile);
 
         TEST_CASE(redundant_config);
@@ -2634,6 +2635,18 @@ private:
         ASSERT_EQUALS("\n\n\n\n\n\n$char me;\n", preprocessor.getcode(filedata, "A", "a.cpp"));
     }
 
+    void undef_ifdef() {
+        const char filedata[] = "#undef A\n"
+                                "#ifdef A\n"
+                                "123\n"
+                                "#endif\n";
+
+        // Preprocess => actual result..
+        Preprocessor preprocessor(NULL, this);
+        ASSERT_EQUALS("\n\n\n\n", preprocessor.getcode(filedata, "", "a.cpp"));
+        ASSERT_EQUALS("\n\n\n\n", preprocessor.getcode(filedata, "A", "a.cpp"));
+    }
+
     void redundant_config() {
         const char filedata[] = "int main() {\n"
                                 "#ifdef FOO\n"