diff --git a/main_test.go b/main_test.go
index 04af6a3ae..697772da1 100644
--- a/main_test.go
+++ b/main_test.go
@@ -315,7 +315,7 @@ func TestMultifileTranspilation(t *testing.T) {
 				"./tests/multi/main1.c",
 				"./tests/multi/main2.c",
 			},
-			"234",
+			"234ERROR!ERROR!ERROR!",
 		},
 	}
 
diff --git a/preprocessor/preprocessor.go b/preprocessor/preprocessor.go
index a67447274..1a70f2136 100644
--- a/preprocessor/preprocessor.go
+++ b/preprocessor/preprocessor.go
@@ -20,6 +20,33 @@ type entity struct {
 	lines []*string
 }
 
+// isSame - check is Same entities
+func (e *entity) isSame(x *entity) bool {
+	if e.include != x.include {
+		return false
+	}
+	if e.positionInSource != x.positionInSource {
+		return false
+	}
+	if e.other != x.other {
+		return false
+	}
+	if len(e.lines) != len(x.lines) {
+		return false
+	}
+	for k := range e.lines {
+		is := e.lines[k]
+		js := x.lines[k]
+		if len(*is) != len(*js) {
+			return false
+		}
+		if *is != *js {
+			return false
+		}
+	}
+	return true
+}
+
 // Analyze - separation preprocessor code to part
 func Analyze(inputFiles, clangFlags []string) (pp []byte, err error) {
 	var allItems []entity
@@ -32,12 +59,14 @@ func Analyze(inputFiles, clangFlags []string) (pp []byte, err error) {
 	// Merge the entities
 	var lines []string
 	for i := range allItems {
+		// If found same part of preprocess code, then
+		// don't include in result buffer for transpiling
+		// for avoid dublicate of code
 		var found bool
 		for j := 0; j < i; j++ {
-			if allItems[i].include == allItems[j].include &&
-				allItems[i].positionInSource == allItems[j].positionInSource &&
-				allItems[i].other == allItems[j].other {
+			if allItems[i].isSame(&allItems[j]) {
 				found = true
+				break
 			}
 		}
 		if found {
diff --git a/tests/multi/err.h b/tests/multi/err.h
new file mode 100644
index 000000000..b038636e5
--- /dev/null
+++ b/tests/multi/err.h
@@ -0,0 +1,5 @@
+#include <stdio.h>
+
+void ERROR_FUNC(){
+	printf("ERROR!");
+}
diff --git a/tests/multi/main1.c b/tests/multi/main1.c
index f6ed548c3..b7b41ecaf 100644
--- a/tests/multi/main1.c
+++ b/tests/multi/main1.c
@@ -1,11 +1,20 @@
 #include <stdio.h>
 #include "header.h"
 
+#define ERROR_FUNC error
+#include "err.h"
+#undef ERROR_FUNC
+#define ERROR_FUNC errorANOTHER
+#include "err.h"
+
 int main() {
     say_two();
     say_three();
     say_four();
 
+	ERROR_FUNC();
+	error();
+	errorANOTHER();
     return 0;
 }