1 files changed, 7 insertions, 1 deletions
diff --git a/op.c b/op.c
index 689fc18aba..19be53507e 100644
--- a/op.c
+++ b/op.c
@@ -5862,7 +5862,13 @@ Perl_ck_require(pTHX_ OP *o)
 		    --SvCUR(kid->op_sv);
 		}
 	    }
-	    sv_catpvn(kid->op_sv, ".pm", 3);
+	    if (SvREADONLY(kid->op_sv)) {
+		SvREADONLY_off(kid->op_sv);
+		sv_catpvn(kid->op_sv, ".pm", 3);
+		SvREADONLY_on(kid->op_sv);
+	    }
+	    else
+		sv_catpvn(kid->op_sv, ".pm", 3);
 	}
     }
     return ck_fun(o);