diff --git a/class.c b/class.c
index 06b72d9b7c..daaf401497 100644
--- a/class.c
+++ b/class.c
@@ -1463,7 +1463,7 @@ rb_scan_args(int argc, const VALUE *argv, const char *fmt, ...)
 		argc--;
 	}
 	else {
-	    hash = rb_check_convert_type(last, T_HASH, "Hash", "to_hash");
+	    hash = rb_check_hash_type(last);
 	    if (!NIL_P(hash))
 		argc--;
 	}
diff --git a/process.c b/process.c
index 8fa00ffe7d..c8c6b04340 100644
--- a/process.c
+++ b/process.c
@@ -1843,7 +1843,7 @@ rb_exec_getargs(int *argc_p, VALUE **argv_p, int accept_shell, VALUE *env_ret, V
     VALUE hash, prog;
 
     if (0 < *argc_p) {
-        hash = rb_check_convert_type((*argv_p)[*argc_p-1], T_HASH, "Hash", "to_hash");
+        hash = rb_check_hash_type((*argv_p)[*argc_p-1]);
         if (!NIL_P(hash)) {
             *opthash_ret = hash;
             (*argc_p)--;
@@ -1851,7 +1851,7 @@ rb_exec_getargs(int *argc_p, VALUE **argv_p, int accept_shell, VALUE *env_ret, V
     }
 
     if (0 < *argc_p) {
-        hash = rb_check_convert_type((*argv_p)[0], T_HASH, "Hash", "to_hash");
+        hash = rb_check_hash_type((*argv_p)[0]);
         if (!NIL_P(hash)) {
             *env_ret = hash;
             (*argc_p)--;
diff --git a/sprintf.c b/sprintf.c
index c3fc39591d..b41ab9cb39 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -161,7 +161,7 @@ get_hash(volatile VALUE *hash, int argc, const VALUE *argv)
     if (argc != 2) {
 	rb_raise(rb_eArgError, "one hash required");
     }
-    tmp = rb_check_convert_type(argv[1], T_HASH, "Hash", "to_hash");
+    tmp = rb_check_hash_type(argv[1]);
     if (NIL_P(tmp)) {
 	rb_raise(rb_eArgError, "one hash required");
     }
diff --git a/string.c b/string.c
index f2abc4fcf3..c97bfc8047 100644
--- a/string.c
+++ b/string.c
@@ -3616,7 +3616,7 @@ rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
     }
     else {
 	repl = argv[1];
-	hash = rb_check_convert_type(argv[1], T_HASH, "Hash", "to_hash");
+	hash = rb_check_hash_type(argv[1]);
 	if (NIL_P(hash)) {
 	    StringValue(repl);
 	}
@@ -3768,7 +3768,7 @@ str_gsub(int argc, VALUE *argv, VALUE str, int bang)
 	break;
       case 2:
 	repl = argv[1];
-	hash = rb_check_convert_type(argv[1], T_HASH, "Hash", "to_hash");
+	hash = rb_check_hash_type(argv[1]);
 	if (NIL_P(hash)) {
 	    StringValue(repl);
 	}