1 files changed, 9 insertions, 1 deletions

diff --git a/sprintf.c b/sprintf.c
index 580a54ae8f..22c8c12d1c 100644
--- a/sprintf.c
+++ b/sprintf.c
@@ -394,7 +394,15 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
 		VALUE val = GETARG();
 		char c;
 
-		c = NUM2INT(val) & 0xff;
+		if (rb_check_string_type(val)) {
+		    if (RSTRING(val)->len != 1) {
+			rb_raise(rb_eArgError, "%%c requires a character");
+		    }
+		    c = RSTRING(val)->ptr[0];
+		}
+		else {
+		    c = NUM2INT(val) & 0xff;
+		}
 		if (!(flags & FWIDTH)) {
 		    PUSH(&c, 1);
 		}