diff --git a/v2/engine/execcmd.h b/v2/engine/execcmd.h
index c46c472e0..e3e4019e7 100644
--- a/v2/engine/execcmd.h
+++ b/v2/engine/execcmd.h
@@ -32,7 +32,7 @@ typedef void (* ExecCmdCallback)
 (
     void * closure,
     int status,
-    timing_info *,
+    timing_info const *,
     char const * invoked_command,
     char const * command_output
 );
diff --git a/v2/engine/make1.c b/v2/engine/make1.c
index 8580bfa03..36d06f916 100644
--- a/v2/engine/make1.c
+++ b/v2/engine/make1.c
@@ -99,7 +99,7 @@ static void make1atail  ( state * );
 static void make1b      ( state * );
 static void make1c      ( state * );
 static void make1d      ( state * );
-static void make_closure( void * closure, int status, timing_info *,
+static void make_closure( void * closure, int status, timing_info const *,
     char const *, char const * );
 
 typedef struct _stack
@@ -807,7 +807,7 @@ static void make_closure
 (
     void * closure,
     int status,
-    timing_info * time,
+    timing_info const * time,
     char const * executed_command,
     char const * command_output
 )