diff --git a/src/pl/plpython/expected/plpython_test.out b/src/pl/plpython/expected/plpython_test.out
index 7b76faf..f8270a7 100644
--- a/src/pl/plpython/expected/plpython_test.out
+++ b/src/pl/plpython/expected/plpython_test.out
@@ -16,8 +16,8 @@ select stupidn();
  zarkon
 (1 row)
 
--- test multiple arguments
-CREATE FUNCTION argument_test_one(u users, a1 text, a2 text) RETURNS text
+-- test multiple arguments and odd characters in function name
+CREATE FUNCTION "Argument test #1"(u users, a1 text, a2 text) RETURNS text
 	AS
 'keys = list(u.keys())
 keys.sort()
@@ -27,8 +27,8 @@ for key in keys:
 words = a1 + " " + a2 + " => {" + ", ".join(out) + "}"
 return words'
 	LANGUAGE plpythonu;
-select argument_test_one(users, fname, lname) from users where lname = 'doe' order by 1;
-                           argument_test_one                           
+select "Argument test #1"(users, fname, lname) from users where lname = 'doe' order by 1;
+                           Argument test #1                            
 -----------------------------------------------------------------------
  jane doe => {fname: jane, lname: doe, userid: 1, username: j_doe}
  john doe => {fname: john, lname: doe, userid: 2, username: johnd}
diff --git a/src/pl/plpython/plpy_procedure.c b/src/pl/plpython/plpy_procedure.c
index e1f5620..4bfc43d 100644
--- a/src/pl/plpython/plpy_procedure.c
+++ b/src/pl/plpython/plpy_procedure.c
@@ -141,6 +141,8 @@ static PLyProcedure *
 PLy_procedure_create(HeapTuple procTup, Oid fn_oid, bool is_trigger)
 {
 	char		procName[NAMEDATALEN + 256];
+	char		rawProcName[NAMEDATALEN];
+	char		*ptr, *ptr2;
 	Form_pg_proc procStruct;
 	PLyProcedure *volatile proc;
 	MemoryContext cxt;
@@ -148,9 +150,22 @@ PLy_procedure_create(HeapTuple procTup, Oid fn_oid, bool is_trigger)
 	int			rv;
 
 	procStruct = (Form_pg_proc) GETSTRUCT(procTup);
+
+	/* Swap invalid chars with '_' before building full name */
+	ptr = NameStr(procStruct->proname);
+	ptr2 = rawProcName;
+	while (*ptr)
+	{
+		if ( (*ptr >= 'A' && *ptr <= 'Z' ) ||
+				(*ptr >= 'a' && *ptr <= 'z' ) ||
+				(*ptr >= '0' && *ptr <= '9' ) )
+			*ptr2++ = *ptr;
+		ptr++;
+	}
+	*ptr2 = 0;
 	rv = snprintf(procName, sizeof(procName),
 				  "__plpython_procedure_%s_%u",
-				  NameStr(procStruct->proname),
+				  rawProcName,
 				  fn_oid);
 	if (rv >= sizeof(procName) || rv < 0)
 		elog(ERROR, "procedure name would overrun buffer");
diff --git a/src/pl/plpython/sql/plpython_test.sql b/src/pl/plpython/sql/plpython_test.sql
index c8d5ef5..3a76104 100644
--- a/src/pl/plpython/sql/plpython_test.sql
+++ b/src/pl/plpython/sql/plpython_test.sql
@@ -11,8 +11,8 @@ CREATE FUNCTION stupidn() RETURNS text AS 'return "zarkon"' LANGUAGE plpython2u;
 
 select stupidn();
 
--- test multiple arguments
-CREATE FUNCTION argument_test_one(u users, a1 text, a2 text) RETURNS text
+-- test multiple arguments and odd characters in function name
+CREATE FUNCTION "Argument test #1"(u users, a1 text, a2 text) RETURNS text
 	AS
 'keys = list(u.keys())
 keys.sort()
@@ -23,7 +23,7 @@ words = a1 + " " + a2 + " => {" + ", ".join(out) + "}"
 return words'
 	LANGUAGE plpythonu;
 
-select argument_test_one(users, fname, lname) from users where lname = 'doe' order by 1;
+select "Argument test #1"(users, fname, lname) from users where lname = 'doe' order by 1;
 
 
 -- check module contents