diff --git a/src/comp/middle/trans.rs b/src/comp/middle/trans.rs
index b9ebc167dff95..825fa20f916fd 100644
--- a/src/comp/middle/trans.rs
+++ b/src/comp/middle/trans.rs
@@ -17,6 +17,8 @@ import middle.ty;
 import back.x86;
 import back.abi;
 
+import pretty.pprust;
+
 import middle.ty.pat_ty;
 import middle.ty.plain_ty;
 
@@ -4910,8 +4912,7 @@ fn trans_log(@block_ctxt cx, @ast.expr e) -> result {
 fn trans_check_expr(@block_ctxt cx, @ast.expr e) -> result {
     auto cond_res = trans_expr(cx, e);
 
-    // FIXME: need pretty-printer.
-    auto expr_str = "<expr>";
+    auto expr_str = pretty.pprust.expr_to_str(e);
     auto fail_cx = new_sub_block_ctxt(cx, "fail");
     auto fail_res = trans_fail(fail_cx, e.span, expr_str);
 
diff --git a/src/comp/pretty/pprust.rs b/src/comp/pretty/pprust.rs
index b0d6fb94187fe..28f64c89d2c3b 100644
--- a/src/comp/pretty/pprust.rs
+++ b/src/comp/pretty/pprust.rs
@@ -379,6 +379,11 @@ impure fn print_literal(ps s, @ast.lit lit) {
             wrd(s.s, common.istr(val as int));
             wrd(s.s, common.ty_mach_to_str(mach));
         }
+        case (ast.lit_mach_float(?mach,?val)) {
+            // val is already a str
+            wrd(s.s, val);
+            wrd(s.s, common.ty_mach_to_str(mach));
+        }
         case (ast.lit_nil) {wrd(s.s, "()");}
         case (ast.lit_bool(?val)) {
             if (val) {wrd(s.s, "true");} else {wrd(s.s, "false");}