diff --git a/src/libcollections/str.rs b/src/libcollections/str.rs
index bbed943fc70..d6ee4dc5f67 100644
--- a/src/libcollections/str.rs
+++ b/src/libcollections/str.rs
@@ -199,7 +199,7 @@ impl<'a> Iterator for Decompositions<'a> {
         }
 
         if !self.sorted {
-            for ch in self.iter {
+            for ch in self.iter.by_ref() {
                 let buffer = &mut self.buffer;
                 let sorted = &mut self.sorted;
                 {
@@ -2154,7 +2154,7 @@ mod tests {
         let s = "ศไทย中华Việt Nam";
         let mut it = s.chars();
         it.next();
-        assert!(it.zip(it.clone()).all(|(x,y)| x == y));
+        assert!(it.clone().zip(it).all(|(x,y)| x == y));
     }
 
     #[test]
diff --git a/src/libstd/collections/hash/map.rs b/src/libstd/collections/hash/map.rs
index cef0b4034f4..b1c1dd1a9f6 100644
--- a/src/libstd/collections/hash/map.rs
+++ b/src/libstd/collections/hash/map.rs
@@ -1731,7 +1731,6 @@ mod test_map {
     }
 
     #[test]
-    #[ignore]  // FIXME(japaric)
     fn test_move_iter_drops() {
         DROP_VECTOR.with(|v| {
             *v.borrow_mut() = repeat(0).take(200).collect();
@@ -1773,7 +1772,7 @@ mod test_map {
                 }
             });
 
-            for _ in half {}
+            for _ in half.by_ref() {}
 
             DROP_VECTOR.with(|v| {
                 let nk = (0u..100).filter(|&i| {
diff --git a/src/libstd/rt/backtrace.rs b/src/libstd/rt/backtrace.rs
index 089dd5fa280..f2d66e1a4d7 100644
--- a/src/libstd/rt/backtrace.rs
+++ b/src/libstd/rt/backtrace.rs
@@ -48,7 +48,6 @@ mod test {
     }) }
 
     #[test]
-    #[ignore]  // FIXME(japaric)
     fn demangle() {
         t!("test", "test");
         t!("_ZN4testE", "test");
@@ -57,7 +56,6 @@ mod test {
     }
 
     #[test]
-    #[ignore]  // FIXME(japaric)
     fn demangle_dollars() {
         t!("_ZN4$UP$E", "Box");
         t!("_ZN8$UP$testE", "Boxtest");
@@ -66,14 +64,12 @@ mod test {
     }
 
     #[test]
-    #[ignore]  // FIXME(japaric)
     fn demangle_many_dollars() {
         t!("_ZN14test$u{20}test4foobE", "test test::foob");
         t!("_ZN12test$UP$test4foobE", "testBoxtest::foob");
     }
 
     #[test]
-    #[ignore]  // FIXME(japaric)
     fn demangle_windows() {
         t!("ZN4testE", "test");
         t!("ZN14test$u{20}test4foobE", "test test::foob");
diff --git a/src/libstd/sys/common/backtrace.rs b/src/libstd/sys/common/backtrace.rs
index c3e12586829..a71676c6bf2 100644
--- a/src/libstd/sys/common/backtrace.rs
+++ b/src/libstd/sys/common/backtrace.rs
@@ -54,7 +54,7 @@ pub fn demangle(writer: &mut Writer, s: &str) -> IoResult<()> {
         let mut chars = inner.chars();
         while valid {
             let mut i = 0;
-            for c in chars {
+            for c in chars.by_ref() {
                 if c.is_numeric() {
                     i = i * 10 + c as uint - '0' as uint;
                 } else {
diff --git a/src/test/run-pass/backtrace.rs b/src/test/run-pass/backtrace.rs
index 781e79257ed..af1cc3b1f4d 100644
--- a/src/test/run-pass/backtrace.rs
+++ b/src/test/run-pass/backtrace.rs
@@ -10,7 +10,6 @@
 
 // no-pretty-expanded FIXME #15189
 // ignore-windows FIXME #13259
-// ignore-test FIXME(japaric)
 
 #![feature(unboxed_closures)]
 #![feature(unsafe_destructor)]