diff --git a/simplecpp.cpp b/simplecpp.cpp
index 5ab6aa30..57b55e91 100644
--- a/simplecpp.cpp
+++ b/simplecpp.cpp
@@ -3740,11 +3740,23 @@ void simplecpp::preprocess(simplecpp::TokenList &output, const simplecpp::TokenL
                     conditionIsTrue = false;
                 }
                 else if (rawtok->str() == IFDEF) {
-                    conditionIsTrue = (macros.find(rawtok->next->str()) != macros.end() || (hasInclude && rawtok->next->str() == HAS_INCLUDE));
-                    maybeUsedMacros[rawtok->next->str()].emplace_back(rawtok->next->location);
+                    const std::string &name = rawtok->next->str();
+                    conditionIsTrue = (macros.find(name) != macros.end() || (hasInclude && name == HAS_INCLUDE));
+                    maybeUsedMacros[name].emplace_back(rawtok->next->location);
+                    if (ifCond) {
+                        const std::string E = conditionIsTrue ? "1" : "0";
+                        const long long result = conditionIsTrue ? 1 : 0;
+                        ifCond->emplace_back(rawtok->location, E, result);
+                    }
                 } else if (rawtok->str() == IFNDEF) {
-                    conditionIsTrue = (macros.find(rawtok->next->str()) == macros.end() && !(hasInclude && rawtok->next->str() == HAS_INCLUDE));
-                    maybeUsedMacros[rawtok->next->str()].emplace_back(rawtok->next->location);
+                    const std::string &name = rawtok->next->str();
+                    conditionIsTrue = (macros.find(name) == macros.end() && !(hasInclude && name == HAS_INCLUDE));
+                    maybeUsedMacros[name].emplace_back(rawtok->next->location);
+                    if (ifCond) {
+                        const std::string E = conditionIsTrue ? "1" : "0";
+                        const long long result = conditionIsTrue ? 1 : 0;
+                        ifCond->emplace_back(rawtok->location, E, result);
+                    }
                 } else { /*if (rawtok->str() == IF || rawtok->str() == ELIF)*/
                     TokenList expr(files);
                     for (const Token *tok = rawtok->next; tok && tok->location.sameline(rawtok->location); tok = tok->next) {
diff --git a/test.cpp b/test.cpp
index 1771526c..76c45ecf 100644
--- a/test.cpp
+++ b/test.cpp
@@ -4026,6 +4026,27 @@ static void ifCond()
         ASSERT_EQUALS("0", it->E);
         ASSERT_EQUALS(0, it->result);
     }
+    {
+        const char code[] = "#ifdef NOTDEFINED\n"
+                            "#endif\n"
+                            "#ifndef NOTDEFINED\n"
+                            "#endif\n";
+        std::list<simplecpp::IfCond> ifCond;
+        ASSERT_EQUALS("", preprocess(code, &ifCond));
+        ASSERT_EQUALS(2, ifCond.size());
+        auto it = ifCond.cbegin();
+        ASSERT_EQUALS(0, it->location.fileIndex);
+        ASSERT_EQUALS(1, it->location.line);
+        ASSERT_EQUALS(2, it->location.col);
+        ASSERT_EQUALS("0", it->E);
+        ASSERT_EQUALS(0, it->result);
+        ++it;
+        ASSERT_EQUALS(0, it->location.fileIndex);
+        ASSERT_EQUALS(3, it->location.line);
+        ASSERT_EQUALS(2, it->location.col);
+        ASSERT_EQUALS("1", it->E);
+        ASSERT_EQUALS(1, it->result);
+    }
 }
 
 static void macroUsage()