diff --git a/.github/workflows/ccpp.yaml b/.github/workflows/ccpp.yaml
index 62d8f3b..c166713 100644
--- a/.github/workflows/ccpp.yaml
+++ b/.github/workflows/ccpp.yaml
@@ -2,9 +2,9 @@ name: C/C++ CI
 
 on:
   push:
-    branches: [ '1.10' ]
+    branches: [ '1.10', '1.11']
   pull_request:
-    branches: [ '1.10' ]
+    branches: [ '1.10', '1.11' ]
 
 jobs:
   build:
diff --git a/src/bin/open_jtalk.c b/src/bin/open_jtalk.c
index e84c280..202d26b 100644
--- a/src/bin/open_jtalk.c
+++ b/src/bin/open_jtalk.c
@@ -172,8 +172,8 @@ static int Open_JTalk_synthesis(Open_JTalk * open_jtalk, const char *txt, FILE *
    int result = 0;
    char buff[MAXBUFLEN];
 
-   errno_t mecab_result = text2mecab(buff, MAXBUFLEN, txt);
-   if (mecab_result != 0) {
+   text2mecab_result_t mecab_result = text2mecab(buff, MAXBUFLEN, txt);
+   if (mecab_result != TEXT2MECAB_SUCCESS) {
       return 0;
    }
    Mecab_analysis(&open_jtalk->mecab, buff);
diff --git a/src/text2mecab/text2mecab.c b/src/text2mecab/text2mecab.c
index 198e214..a34ae85 100644
--- a/src/text2mecab/text2mecab.c
+++ b/src/text2mecab/text2mecab.c
@@ -92,10 +92,10 @@ static int strtopcmp(const char *str, const char *pattern)
    }
 }
 
-errno_t text2mecab(char *output, size_t sizeOfOutput, const char *input)
+text2mecab_result_t text2mecab(char *output, size_t sizeOfOutput, const char *input)
 {
    if (input == NULL || output == NULL || sizeOfOutput == 0)
-      return EINVAL;
+      return TEXT2MECAB_RESULT_INVALID_ARGUMENT;
 
    int i, j;
    const int length = strlen(input);
@@ -117,7 +117,7 @@ errno_t text2mecab(char *output, size_t sizeOfOutput, const char *input)
          str = text2mecab_conv_list[i + 1];
          if (index + strlen(str) >= sizeOfOutput) {
             output[0] = '\0';
-            return ERANGE;
+            return TEXT2MECAB_RESULT_RANGE_ERROR;
          }
          for (j = 0; str[j] != '\0'; j++)
             output[index++] = str[j];
@@ -136,7 +136,7 @@ errno_t text2mecab(char *output, size_t sizeOfOutput, const char *input)
          if (e > 0) {
             if (index + e >= sizeOfOutput) {
                output[0] = '\0';
-               return ERANGE;
+               return TEXT2MECAB_RESULT_RANGE_ERROR;
             }
             for (j = 0; j < e; j++)
                output[index++] = input[s++];
@@ -148,7 +148,7 @@ errno_t text2mecab(char *output, size_t sizeOfOutput, const char *input)
       }
    }
    output[index] = '\0';
-   return 0;
+   return TEXT2MECAB_RESULT_SUCCESS;
 }
 
 TEXT2MECAB_C_END;
diff --git a/src/text2mecab/text2mecab.h b/src/text2mecab/text2mecab.h
index bb1eba1..2878a30 100644
--- a/src/text2mecab/text2mecab.h
+++ b/src/text2mecab/text2mecab.h
@@ -51,7 +51,13 @@
 
 TEXT2MECAB_H_START;
 
-errno_t text2mecab(char *output, size_t sizeOfOutput, const char *input);
+typedef enum {
+    TEXT2MECAB_RESULT_SUCCESS = 0,
+    TEXT2MECAB_RESULT_INVALID_ARGUMENT = 1,
+    TEXT2MECAB_RESULT_RANGE_ERROR = 2,
+} text2mecab_result_t;
+
+text2mecab_result_t text2mecab(char *output, size_t sizeOfOutput, const char *input);
 
 TEXT2MECAB_H_END;