diff --git a/.gitignore b/.gitignore
index ad0839c..f0bba75 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,4 +2,5 @@ target/
 firedbg/
 Cargo.lock
 *.sublime*
-.vscode
\ No newline at end of file
+.vscode
+.DS_Store
\ No newline at end of file
diff --git a/src/mysql/probe.rs b/src/mysql/probe.rs
index ecb0c47..871df1c 100644
--- a/src/mysql/probe.rs
+++ b/src/mysql/probe.rs
@@ -22,7 +22,7 @@ impl SchemaProbe for MySql {
             .take()
     }
 
-    fn has_index<T, C>(table: T, index: C) -> SelectStatement
+    fn has_index<T, C>(&self, table: T, index: C) -> SelectStatement
     where
         T: AsRef<str>,
         C: AsRef<str>,
diff --git a/src/postgres/probe.rs b/src/postgres/probe.rs
index eeaaf86..0067674 100644
--- a/src/postgres/probe.rs
+++ b/src/postgres/probe.rs
@@ -24,7 +24,7 @@ impl SchemaProbe for Postgres {
             .take()
     }
 
-    fn has_index<T, C>(table: T, index: C) -> SelectStatement
+    fn has_index<T, C>(&self, table: T, index: C) -> SelectStatement
     where
         T: AsRef<str>,
         C: AsRef<str>,
diff --git a/src/probe.rs b/src/probe.rs
index 4652f2f..fd178f5 100644
--- a/src/probe.rs
+++ b/src/probe.rs
@@ -5,7 +5,7 @@ pub trait SchemaProbe {
 
     fn query_tables() -> SelectStatement;
 
-    fn has_table<T>(table: T) -> SelectStatement
+    fn has_table<T>(&self, table: T) -> SelectStatement
     where
         T: AsRef<str>,
     {
@@ -17,7 +17,7 @@ pub trait SchemaProbe {
             .take()
     }
 
-    fn has_column<T, C>(table: T, column: C) -> SelectStatement
+    fn has_column<T, C>(&self, table: T, column: C) -> SelectStatement
     where
         T: AsRef<str>,
         C: AsRef<str>,
@@ -37,7 +37,7 @@ pub trait SchemaProbe {
             .take()
     }
 
-    fn has_index<T, C>(table: T, index: C) -> SelectStatement
+    fn has_index<T, C>(&self, table: T, index: C) -> SelectStatement
     where
         T: AsRef<str>,
         C: AsRef<str>;
diff --git a/src/sqlite/probe.rs b/src/sqlite/probe.rs
index 5cfd1f3..22f7370 100644
--- a/src/sqlite/probe.rs
+++ b/src/sqlite/probe.rs
@@ -21,7 +21,7 @@ impl SchemaProbe for Sqlite {
             .take()
     }
 
-    fn has_column<T, C>(table: T, column: C) -> SelectStatement
+    fn has_column<T, C>(&self, table: T, column: C) -> SelectStatement
     where
         T: AsRef<str>,
         C: AsRef<str>,
@@ -35,7 +35,7 @@ impl SchemaProbe for Sqlite {
             .take()
     }
 
-    fn has_index<T, C>(table: T, index: C) -> SelectStatement
+    fn has_index<T, C>(&self, table: T, index: C) -> SelectStatement
     where
         T: AsRef<str>,
         C: AsRef<str>,