diff --git a/lib/preprocessor.cpp b/lib/preprocessor.cpp
index 3cc639135..0ff3bd059 100644
--- a/lib/preprocessor.cpp
+++ b/lib/preprocessor.cpp
@@ -1104,10 +1104,13 @@ void Preprocessor::simplifyCondition(const std::map<std::string, std::string> &v
         const std::map<std::string, std::string>::const_iterator it = variables.find(tok->str());
         if (it != variables.end())
         {
-            if (it->second.empty())
-                tok->deleteThis();
-            else
+            if (!it->second.empty())
                 tok->str(it->second);
+            else if ((!tok->previous() || tok->strAt(-1) == "||" || tok->strAt(-1) == "&&" || tok->strAt(-1) == "(") &&
+                     (!tok->next() || tok->strAt(1) == "||" || tok->strAt(1) == "&&" || tok->strAt(-1) == ")"))
+                tok->str("1");
+            else
+                tok->deleteThis();
         }
     }
 
diff --git a/test/testpreprocessor.cpp b/test/testpreprocessor.cpp
index 2427cd2e9..cf1546369 100644
--- a/test/testpreprocessor.cpp
+++ b/test/testpreprocessor.cpp
@@ -111,7 +111,8 @@ private:
         TEST_CASE(if_cond9);
         TEST_CASE(if_cond10);
 
-        TEST_CASE(if_or);
+        TEST_CASE(if_or_1);
+        TEST_CASE(if_or_2);
 
         TEST_CASE(multiline1);
         TEST_CASE(multiline2);
@@ -1068,7 +1069,7 @@ private:
 
 
 
-    void if_or()
+    void if_or_1()
     {
         const char filedata[] = "#if defined(DEF_10) || defined(DEF_11)\n"
                                 "a1;\n"
@@ -1097,6 +1098,15 @@ private:
 
     }
 
+    void if_or_2()
+    {
+        const std::string code("#if X || Y\n"
+                               "a1;\n"
+                               "#endif\n");
+        const std::string actual = Preprocessor::getcode(code, "X", "test.c", NULL);
+        ASSERT_EQUALS("\na1;\n\n", actual);
+    }
+
 
     void multiline1()
     {