diff --git a/envy24control/strstr_icase_blank.c b/envy24control/strstr_icase_blank.c
index af44854..4c325cf 100644
--- a/envy24control/strstr_icase_blank.c
+++ b/envy24control/strstr_icase_blank.c
@@ -48,7 +48,6 @@ int strstr_icase_blank(const char * const string1, const char * const string2)
 	char search_string[MAX_SEARCH_FIELD_LENGTH];
 	char *pstr;
 	int pos_first_non_blank;
-	int isblank(int c);
 
 	strncpy(search_string, string2, MAX_SEARCH_FIELD_LENGTH);
 	search_string[MAX_SEARCH_FIELD_LENGTH - 1] = '\0';