diff --git a/Lib/guile/guiledec.swg b/Lib/guile/guiledec.swg
index e6ae7032b..2a285e7d9 100644
--- a/Lib/guile/guiledec.swg
+++ b/Lib/guile/guiledec.swg
@@ -45,6 +45,13 @@ GSWIG_scm2str (SCM s)
   return gh_scm2newstr (s, &len);
 }
 
+static char
+GSWIG_scm2char (SCM s)
+{
+  if (SCM_CHARP(s)) return SCM_CHAR(s);
+  scm_wrong_type_arg(NULL, 0, s);
+}
+
 typedef struct SwigPtrType SwigPtrType;
 
 typedef struct _swig_type_info {
diff --git a/Lib/guile/typemaps.i b/Lib/guile/typemaps.i
index 4f5aa8a0e..27f14bb56 100644
--- a/Lib/guile/typemaps.i
+++ b/Lib/guile/typemaps.i
@@ -29,8 +29,8 @@
 %enddef
  
  SIMPLE_MAP(bool, gh_scm2bool, gh_bool2scm, boolean);
- SIMPLE_MAP(char, gh_scm2char, gh_char2scm, char);
- SIMPLE_MAP(unsigned char, gh_scm2char, gh_char2scm, char);
+ SIMPLE_MAP(char, GSWIG_scm2char, gh_char2scm, char);
+ SIMPLE_MAP(unsigned char, GSWIG_scm2char, gh_char2scm, char);
  SIMPLE_MAP(int, gh_scm2int, gh_int2scm, integer);
  SIMPLE_MAP(short, gh_scm2int, gh_int2scm, integer);
  SIMPLE_MAP(long, gh_scm2long, gh_long2scm, integer);
diff --git a/Source/Modules1.1/guile.cxx b/Source/Modules1.1/guile.cxx
index f3c0f937f..26e4f5e33 100644
--- a/Source/Modules1.1/guile.cxx
+++ b/Source/Modules1.1/guile.cxx
@@ -474,6 +474,7 @@ GUILE::create_function (char *name, char *iname, SwigType *d, ParmList *l)
   int i;
   int numargs = 0;
   int numopt = 0;
+  int pcount = 0;
 
   // Make a wrapper name for this
   char * wname = new char [strlen (prefix) + strlen (iname) + 2];
@@ -484,7 +485,8 @@ GUILE::create_function (char *name, char *iname, SwigType *d, ParmList *l)
   Replace(proc_name,"_", "-", DOH_REPLACE_ANY);
 
   /* Emit locals etc. into f->code; figure out which args to ignore */
-  emit_args (d, l, f);
+  pcount = emit_args (d, l, f);
+  numopt = check_numopt(l);
 
   /* Declare return variable */
 
@@ -516,6 +518,8 @@ GUILE::create_function (char *name, char *iname, SwigType *d, ParmList *l)
     else {
       if (numargs!=0) Printf(f->def,", ");
       Printf(f->def,"SCM s_%d", i);
+      if (i>=(pcount-numopt))
+	Printf(f->code,"    if (s_%d != GH_NOT_PASSED) {\n", i);
       ++numargs;
       if (guile_do_typemap(f->code, "in", pt, pn,
 			   source, target, numargs, proc_name, f, 0)) {
@@ -533,6 +537,8 @@ GUILE::create_function (char *name, char *iname, SwigType *d, ParmList *l)
 	guile_do_doc_typemap(signature, "indoc", pt, pn,
 			     numargs, proc_name, f);
       }
+      if (i>=(pcount-numopt))
+	Printf(f->code,"    }\n");
     }
 
     /* Check if there are any constraints. */