diff --git a/src/session/download.c b/src/session/download.c
index bed83952b..da7181d8e 100644
--- a/src/session/download.c
+++ b/src/session/download.c
@@ -785,6 +785,9 @@ static unsigned char *
 subst_file(unsigned char *prog, unsigned char *file)
 {
 	struct string name;
+	/* When there is no %s in the mailcap entry, the handler program reads
+	 * data from stdin instead of a file. */
+	int input = 1;
 
 	if (!init_string(&name)) return NULL;
 
@@ -797,6 +800,7 @@ subst_file(unsigned char *prog, unsigned char *file)
 		prog += p;
 
 		if (*prog == '%') {
+			input = 0;
 #if defined(HAVE_CYGWIN_CONV_TO_FULL_WIN32_PATH)
 #ifdef MAX_PATH
 			unsigned char new_path[MAX_PATH];
@@ -813,6 +817,19 @@ subst_file(unsigned char *prog, unsigned char *file)
 		}
 	}
 
+	if (input) {
+		struct string s;
+
+		if (init_string(&s)) {
+			add_to_string(&s, "/bin/cat ");
+			add_char_to_string(&s, '"');
+			add_to_string(&s, file);
+			add_to_string(&s, "\" | ");
+			add_string_to_string(&s, &name);
+			done_string(&name);
+			return s.source;
+		}
+	}
 	return name.source;
 }