diff --git a/parsesql.c b/parsesql.c
index 5c3cc5b..e45e946 100644
--- a/parsesql.c
+++ b/parsesql.c
@@ -37,6 +37,11 @@ struct SQL_Token {
 typedef struct SQL_Token SQL_Token;
 
 
+static is_hostvar_char(char c)
+{
+    return isalnum(c) || c == '_';
+}
+
 size_t sql_count_host_vars(const char *s)
 {
   size_t ret = 0;
@@ -49,7 +54,7 @@ size_t sql_count_host_vars(const char *s)
     if (!a || b<a) {
       ++ret;
       pos = b + 1;
-      for (; isalnum(*pos); ++pos)
+      for (; is_hostvar_char(*pos); ++pos)
         ;
       if (*pos == ':')
         ++pos;
@@ -97,7 +102,7 @@ int sql_tokenize(const char *s,
       }
       const char *str_pos = b+1;
       for (;;) {
-        for (; isalnum(*str_pos); ++str_pos)
+        for (; is_hostvar_char(*str_pos); ++str_pos)
           ;
         if (*str_pos != ':')
           break;
diff --git a/unittest/test_parsesql.c b/unittest/test_parsesql.c
index 146ea9e..16b8398 100644
--- a/unittest/test_parsesql.c
+++ b/unittest/test_parsesql.c
@@ -195,6 +195,39 @@ START_TEST(token_06)
 }
 END_TEST
 
+START_TEST(token_07)
+{
+  const char inp[] = "foo :xyz_id bar in :ab_id:ab_id_ind blah);";
+  SQL_Token *tokens = 0;
+  size_t size = 0;
+  int ret = sql_tokenize(inp, &tokens, &size);
+  ck_assert_int_eq(ret, 0);
+  ck_assert(size>3);
+  struct st {
+    const char *a;
+    bool b;
+  };
+  typedef struct st st;
+  const st src[] = {
+    { "foo ", false },
+    { ":xyz_id", true },
+    { " bar in ", false },
+    { ":ab_id:ab_id_ind", true },
+    { " blah);", false },
+    { 0, 0}
+  };
+  for (size_t i = 0; i<5; ++i) {
+    ck_assert(tokens[i].host_var == src[i].b);
+    char b[128] = {0};
+    strncpy(b, tokens[i].begin, tokens[i].end - tokens[i].begin);
+    ck_assert_str_eq(b, src[i].a);
+  }
+  ck_assert(!tokens[5].begin);
+  ck_assert(!tokens[5].end);
+  free(tokens);
+}
+END_TEST
+
 START_TEST(quote_01)
 {
   char out[32] = {0};
@@ -319,6 +352,7 @@ TCase *parsesql_tc_create()
   tcase_add_test(tc, token_04);
   tcase_add_test(tc, token_05);
   tcase_add_test(tc, token_06);
+  tcase_add_test(tc, token_07);
   tcase_add_test(tc, quote_01);
   tcase_add_test(tc, quote_02);
   tcase_add_test(tc, quote_03);