diff --git a/src/trace.rs b/src/trace.rs
index de03742..b3c9939 100644
--- a/src/trace.rs
+++ b/src/trace.rs
@@ -1,3 +1,4 @@
+//! Tracing and profiling functions. Error and warning log.
 use libc::{c_char, c_int, c_void};
 use std::ffi::CString;
 use std::ptr;
@@ -30,12 +31,16 @@ pub fn log(err_code: c_int, msg: &str) {
     }
 }
 
+/// The trace callback function signature.
 pub type TraceCallback =
     Option<extern "C" fn (p_arg: *mut c_void, z_sql: *const c_char)>;
+/// The profile callback function signature.
 pub type ProfileCallback =
     Option<extern "C" fn (p_arg: *mut c_void, z_sql: *const c_char, nanoseconds: u64)>;
+
 impl SqliteConnection {
     /// Register or clear a callback function that can be used for tracing the execution of SQL statements.
+    ///
     /// Prepared statement placeholders are replaced/logged with their assigned values.
     /// There can only be a single tracer defined for each database connection.
     /// Setting a new tracer clears the old one.
@@ -44,6 +49,7 @@ impl SqliteConnection {
         unsafe { ffi::sqlite3_trace(c.db(), x_trace, ptr::null_mut()); }
     }
     /// Register or clear a callback function that can be used for profiling the execution of SQL statements.
+    ///
     /// There can only be a single profiler defined for each database connection.
     /// Setting a new profiler clears the old one.
     pub fn profile(&mut self, x_profile: ProfileCallback) {