diff --git a/src/arduino.cc/builder/ctags/ctags_parser.go b/src/arduino.cc/builder/ctags/ctags_parser.go
index 55497155..318c679b 100644
--- a/src/arduino.cc/builder/ctags/ctags_parser.go
+++ b/src/arduino.cc/builder/ctags/ctags_parser.go
@@ -130,7 +130,7 @@ func removeDuplicate(tags []*types.CTag) {
 	definedPrototypes := make(map[string]bool)
 
 	for _, tag := range tags {
-		if !definedPrototypes[tag.Prototype] {
+		if !definedPrototypes[tag.Prototype] && tag.SkipMe == false {
 			definedPrototypes[tag.Prototype] = true
 		} else {
 			tag.SkipMe = true
diff --git a/src/arduino.cc/builder/ctags_target_file_saver.go b/src/arduino.cc/builder/ctags_target_file_saver.go
index 0f3277ca..5df0d40d 100644
--- a/src/arduino.cc/builder/ctags_target_file_saver.go
+++ b/src/arduino.cc/builder/ctags_target_file_saver.go
@@ -34,6 +34,8 @@ import (
 	"arduino.cc/builder/types"
 	"arduino.cc/builder/utils"
 	"path/filepath"
+	"strconv"
+	"strings"
 )
 
 type CTagsTargetFileSaver struct {
@@ -50,6 +52,12 @@ func (s *CTagsTargetFileSaver) Run(ctx *types.Context) error {
 		return i18n.WrapError(err)
 	}
 
+	// drop every line which is not part of user sketch or a define/ifdef/endif/etc
+	var searchSlice []string
+	searchSlice = append(searchSlice, filepath.Dir(ctx.SketchLocation))
+	searchSlice = append(searchSlice, filepath.Dir(ctx.BuildPath))
+	source = saveLinesContainingDirectivesAndSketch(source, searchSlice)
+
 	ctagsTargetFilePath := filepath.Join(preprocPath, s.TargetFileName)
 	err = utils.WriteFile(ctagsTargetFilePath, source)
 	if err != nil {
@@ -60,3 +68,52 @@ func (s *CTagsTargetFileSaver) Run(ctx *types.Context) error {
 
 	return nil
 }
+
+func saveLinesContainingDirectivesAndSketch(src string, tofind []string) string {
+	lines := strings.Split(src, "\n")
+
+	saveLine := false
+	minimizedString := ""
+
+	for _, line := range lines {
+		if saveLine || startsWithHashtag(line) {
+			minimizedString += line + "\n"
+		}
+		if containsAny(line, tofind) && isLineMarker(line) {
+			saveLine = true
+		}
+		if saveLine && !containsAny(line, tofind) && isLineMarker(line) {
+			saveLine = false
+		}
+	}
+	return minimizedString
+}
+
+func containsAny(src string, tofind []string) bool {
+	for _, str := range tofind {
+		if strings.Contains(src, str) {
+			return true
+		}
+	}
+	return false
+}
+
+func startsWithHashtag(src string) bool {
+	trimmedStr := strings.TrimSpace(src)
+	if len(trimmedStr) > 0 && trimmedStr[0] == '#' {
+		return true
+	}
+	return false
+}
+
+func isLineMarker(src string) bool {
+	trimmedStr := strings.TrimSpace(src)
+	splittedStr := strings.Split(trimmedStr, " ")
+	if len(splittedStr) > 2 && splittedStr[0][0] == '#' {
+		_, err := strconv.Atoi(splittedStr[1])
+		if err == nil {
+			return true
+		}
+	}
+	return false
+}
diff --git a/src/arduino.cc/builder/test/ctags_to_prototypes_test.go b/src/arduino.cc/builder/test/ctags_to_prototypes_test.go
index ca1a2a6b..55dd7abe 100644
--- a/src/arduino.cc/builder/test/ctags_to_prototypes_test.go
+++ b/src/arduino.cc/builder/test/ctags_to_prototypes_test.go
@@ -30,10 +30,13 @@
 package test
 
 import (
+	"arduino.cc/builder"
+	"arduino.cc/builder/constants"
 	"arduino.cc/builder/ctags"
 	"arduino.cc/builder/types"
 	"github.com/stretchr/testify/require"
 	"io/ioutil"
+	"os"
 	"path/filepath"
 	"testing"
 )
@@ -459,3 +462,52 @@ func TestCTagsToPrototypesFunctionPointers(t *testing.T) {
 
 	require.Equal(t, 2, ctx.PrototypesLineWhereToInsert)
 }
+
+func TestCTagsRunnerSketchWithClassFunction(t *testing.T) {
+	DownloadCoresAndToolsAndLibraries(t)
+
+	sketchLocation := Abs(t, filepath.Join("sketch_with_class", "sketch_class_function.ino"))
+
+	ctx := &types.Context{
+		HardwareFolders:         []string{filepath.Join("..", "hardware"), "hardware", "downloaded_hardware"},
+		ToolsFolders:            []string{"downloaded_tools"},
+		BuiltInLibrariesFolders: []string{"downloaded_libraries"},
+		OtherLibrariesFolders:   []string{"libraries"},
+		SketchLocation:          sketchLocation,
+		FQBN:                    "arduino:avr:leonardo",
+		ArduinoAPIVersion:       "10600",
+		Verbose:                 true,
+	}
+
+	buildPath := SetupBuildPath(t, ctx)
+	defer os.RemoveAll(buildPath)
+
+	commands := []types.Command{
+
+		&builder.ContainerSetupHardwareToolsLibsSketchAndProps{},
+
+		&builder.ContainerMergeCopySketchFiles{},
+
+		&builder.ContainerFindIncludes{},
+
+		&builder.PrintUsedLibrariesIfVerbose{},
+		&builder.WarnAboutArchIncompatibleLibraries{},
+		&builder.CTagsTargetFileSaver{Source: &ctx.Source, TargetFileName: constants.FILE_CTAGS_TARGET},
+		&ctags.CTagsRunner{},
+		&ctags.CTagsParser{},
+		&CollectCtagsFromPreprocSource{},
+		&ctags.CTagsToPrototypes{},
+	}
+
+	for _, command := range commands {
+		err := command.Run(ctx)
+		NoError(t, err)
+	}
+
+	prototypes := ctx.Prototypes
+
+	require.Equal(t, 3, len(prototypes))
+	require.Equal(t, "void setup();", prototypes[0].Prototype)
+	require.Equal(t, "void loop();", prototypes[1].Prototype)
+	require.Equal(t, "void asdf();", prototypes[2].Prototype)
+}
diff --git a/src/arduino.cc/builder/test/sketch_with_class/sketch_class_function.ino b/src/arduino.cc/builder/test/sketch_with_class/sketch_class_function.ino
new file mode 100644
index 00000000..45250090
--- /dev/null
+++ b/src/arduino.cc/builder/test/sketch_with_class/sketch_class_function.ino
@@ -0,0 +1,8 @@
+class test {
+    void asdf() {}
+};
+void setup() {
+  asdf();
+}
+void loop() {}
+void asdf() {}
\ No newline at end of file