diff --git a/libvo/vo_gl.c b/libvo/vo_gl.c
index 0614dbe844..f84065d868 100644
--- a/libvo/vo_gl.c
+++ b/libvo/vo_gl.c
@@ -472,13 +472,6 @@ uninit(void)
   vo_x11_uninit();
 }
 
-static int int_non_neg(int *sh)
-{
-  if ( *sh < 0 )
-    return 0;
-  return 1;
-}
-
 static opt_t subopts[] = {
   {"manyfmts",     OPT_ARG_BOOL, &many_fmts,    NULL},
   {"osd",          OPT_ARG_BOOL, &use_osd,      NULL},
diff --git a/libvo/vo_pnm.c b/libvo/vo_pnm.c
index 68d4866a08..f4e04c39dc 100644
--- a/libvo/vo_pnm.c
+++ b/libvo/vo_pnm.c
@@ -103,16 +103,6 @@ void pnm_write_error(void) {
 
 /* ------------------------------------------------------------------------- */
 
-/** \brief Validation function for maxfiles
- */
-
-static int int_pos(int *mf)
-{
-    if ( *mf > 0 )
-        return 1;
-    return 0;
-}
-
 /** \brief Pre-initialisation.
  *
  * This function is called before initialising the video output driver. It
diff --git a/subopt-helper.c b/subopt-helper.c
index de103e1126..611af73e1f 100644
--- a/subopt-helper.c
+++ b/subopt-helper.c
@@ -263,3 +263,21 @@ static char const * parse_str( char const * const str, strarg_t * const valp )
 
   return match;
 }
+
+
+/*** common test functions ***/
+
+/** \brief Test if i is not negative */
+int int_non_neg( int * i )
+{
+  if ( *i < 0 ) { return 0; }
+
+  return 1;
+}
+/** \brief Test if i is positive. */
+int int_pos( int * i )
+{
+  if ( *i > 0 ) { return 1; }
+
+  return 0;
+}
diff --git a/subopt-helper.h b/subopt-helper.h
index 5891b8c0c8..9a8c828199 100644
--- a/subopt-helper.h
+++ b/subopt-helper.h
@@ -39,4 +39,8 @@ typedef struct strarg_s
   char const * str;  ///< pointer to position inside the parse string
 } strarg_t;
 
+
+int int_non_neg( int * i );
+int int_pos( int * i );
+
 #endif