diff --git a/lib/preprocessor.cpp b/lib/preprocessor.cpp
index 4033f65a7..1497a194b 100644
--- a/lib/preprocessor.cpp
+++ b/lib/preprocessor.cpp
@@ -1450,6 +1450,7 @@ void Preprocessor::simplifyCondition(const std::map<std::string, std::string> &c
     }
 
     // simplify calculations..
+    tokenizer.concatenateNegativeNumber();
     bool modified = true;
     while (modified) {
         modified = false;
diff --git a/test/testpreprocessor.cpp b/test/testpreprocessor.cpp
index b4c05f0c6..6acf223ad 100644
--- a/test/testpreprocessor.cpp
+++ b/test/testpreprocessor.cpp
@@ -222,6 +222,7 @@ private:
         TEST_CASE(define_if1);
         TEST_CASE(define_if2);
         TEST_CASE(define_if3);
+        TEST_CASE(define_if4); // #4079 - #define X +123
         TEST_CASE(define_ifdef);
         TEST_CASE(define_ifndef1);
         TEST_CASE(define_ifndef2);
@@ -2695,6 +2696,15 @@ private:
         ASSERT_EQUALS("\n\nFOO\n\n", preprocessor.getcode(filedata,"",""));
     }
 
+    void define_if4() {
+        const char filedata[] = "#define X +123\n"
+                                 "#if X==123\n"
+                                 "FOO\n"
+                                 "#endif";
+        Preprocessor preprocessor(NULL, this);
+        ASSERT_EQUALS("\n\nFOO\n\n", preprocessor.getcode(filedata,"",""));
+    }
+
     void define_ifdef() {
         {
             const char filedata[] = "#define ABC\n"