diff --git a/src/db.c b/src/db.c
index cc4fb37..cd9c7be 100644
--- a/src/db.c
+++ b/src/db.c
@@ -98,16 +98,16 @@ safeincr (
     debug_assert(argc == 1);
     sqlite3_value *val = argv[0];
 
-    if (unlikely(SQLITE_INTEGER != sqlite3_value_type(val))) {
-        sqlite3_result_error(dbctx, "value is not an integer", -1);
-        return;
+    int64_t ival = 0;
+    if (SQLITE_INTEGER == sqlite3_value_type(val)) {
+        ival = sqlite3_value_int64(val);
+        if (unlikely(ival == INT64_MAX)) {
+            sqlite3_result_error(dbctx, "integer overflow", -1);
+            return;
+        }
+        ++ival;
     }
-    int64_t ival = sqlite3_value_int64(val);
-    if (unlikely(ival == INT64_MAX)) {
-        sqlite3_result_error(dbctx, "integer overflow", -1);
-        return;
-    }
-    sqlite3_result_int64(dbctx, ival + 1);
+    sqlite3_result_int64(dbctx, ival);
 }
 
 int
diff --git a/src/db.h b/src/db.h
index 629a292..e262bd4 100644
--- a/src/db.h
+++ b/src/db.h
@@ -155,8 +155,8 @@ db_query_i64_cb (
  * SQLite converts the result to REAL upon integer overflow.
  * See: <https://www.sqlite.org/datatype3.html#operators>.
  *
- * The `safeincr()` function fails if given a non-integer
- * argument, or if the argument value equals to INT64_MAX.
+ * The `safeincr()` function returns 0 if given a non-integer
+ * argument, and fails if the argument value equals to INT64_MAX.
  */
 int
 db_register_safeincr (