diff --git a/src/CHANGELOG b/src/CHANGELOG
index e987496a3..2604b374e 100644
--- a/src/CHANGELOG
+++ b/src/CHANGELOG
@@ -1528,6 +1528,9 @@ ECLS 0.9b
 
   - READ/WRITE-SEQUENCE implemented.
 
+  - OPEN now accepts the parameter :EXTERNAL-FORMAT, which can only be
+    :DEFAULT, as ECL does not support the notion of external formats
+    (all streams have element type (UNSIGNED-BYTE 8)).
 
 TODO:
 =====
diff --git a/src/c/compiler.d b/src/c/compiler.d
index a9bf0de11..fc9b4488c 100644
--- a/src/c/compiler.d
+++ b/src/c/compiler.d
@@ -347,7 +347,7 @@ FEillegal_variable_name(cl_object v)
 static void
 FEill_formed_input()
 {
-	FEprogram_error("Unproper list handled to the compiler.", 0);
+	FEprogram_error("Improper list handled to the compiler.", 0);
 }
 
 static void
diff --git a/src/c/file.d b/src/c/file.d
index 9b9d437df..5c1771366 100644
--- a/src/c/file.d
+++ b/src/c/file.d
@@ -507,6 +507,8 @@ StdinResume()
  * CLOS-STREAMS and S is an instance object, STREAM-READ-CHAR is invoked
  * to retrieve the character. Then STREAM-READ-CHAR should either
  * output the character, or NIL, indicating EOF.
+ *
+ * INV: ecl_getc(strm) checks the type of STRM.
  */
 int
 ecl_getc(cl_object strm)
@@ -1580,9 +1582,13 @@ cl_output_stream_p(cl_object strm)
 		   (element_type @'base-char')
 		   (if_exists Cnil iesp)
 		   (if_does_not_exist Cnil idnesp)
+	           (external_format @':default')
 	      &aux strm)
 	enum smmode smm;
 @
+	if (external_format != @':default')
+		FEerror("~S is not a valid stream external format.", 1,
+			external_format);
 	/* INV: open_stream() checks types */
 	if (direction == @':input') {
 		smm = smm_input;
diff --git a/src/c/read.d b/src/c/read.d
index be58bb350..27aae6792 100644
--- a/src/c/read.d
+++ b/src/c/read.d
@@ -1517,7 +1517,6 @@ CANNOT_PARSE:
 		   &optional eof_errorp eof_value)
 	int c;
 @
-	assert_type_stream(binary_input_stream);
 	c = ecl_getc(binary_input_stream);
 	if (c == EOF) {
 		if (Null(eof_errorp))
diff --git a/src/c/symbols_list.h b/src/c/symbols_list.h
index 78be9d3d7..0f1b978d7 100644
--- a/src/c/symbols_list.h
+++ b/src/c/symbols_list.h
@@ -1276,6 +1276,7 @@ cl_symbols[] = {
 {KEY_ "EXECUTE", KEYWORD, NULL, -1},
 {KEY_ "EXPECTED-TYPE", KEYWORD, NULL, -1},
 {KEY_ "EXTERNAL", KEYWORD, NULL, -1},
+{KEY_ "EXTERNAL-FORMAT", KEYWORD, NULL, -1},
 {KEY_ "FORMAT-ARGUMENTS", KEYWORD, NULL, -1},
 {KEY_ "FORMAT-CONTROL", KEYWORD, NULL, -1},
 {KEY_ "FUNCTION", KEYWORD, NULL, -1},