diff --git a/src/len_zero.rs b/src/len_zero.rs
index 548a3d92c2c..e61c77adf24 100644
--- a/src/len_zero.rs
+++ b/src/len_zero.rs
@@ -198,7 +198,7 @@ fn has_is_empty(cx: &LateContext, expr: &Expr) -> bool {
         }
         ty::TyProjection(_) => ty.ty_to_def_id().map_or(false, |id| has_is_empty_impl(cx, &id)),
         ty::TyEnum(ref id, _) | ty::TyStruct(ref id, _) => has_is_empty_impl(cx, &id.did),
-        ty::TyArray(..) => true,
+        ty::TyArray(..) | ty::TyStr => true,
         _ => false,
     }
 }
diff --git a/src/panic.rs b/src/panic.rs
index 60a3ce1a461..7dbcf2a5b30 100644
--- a/src/panic.rs
+++ b/src/panic.rs
@@ -37,7 +37,8 @@ impl LateLintPass for PanicPass {
             match_path(path, &BEGIN_UNWIND),
             let ExprLit(ref lit) = params[0].node,
             let LitKind::Str(ref string, _) = lit.node,
-            string.contains('{'),
+            let Some(par) = string.find('{'),
+            string[par..].contains('}'),
             let Some(sp) = cx.sess().codemap()
                              .with_expn_info(expr.span.expn_id,
                                              |info| info.map(|i| i.call_site))
diff --git a/src/utils/mod.rs b/src/utils/mod.rs
index 625e8da197d..ee2e2d7206f 100644
--- a/src/utils/mod.rs
+++ b/src/utils/mod.rs
@@ -383,14 +383,14 @@ fn trim_multiline_inner(s: Cow<str>, ignore_first: bool, ch: char) -> Cow<str> {
     let x = s.lines()
              .skip(ignore_first as usize)
              .filter_map(|l| {
-                 if l.len() > 0 {
+                 if l.is_empty() {
+                     None
+                 } else {
                      // ignore empty lines
                      Some(l.char_indices()
                            .find(|&(_, x)| x != ch)
                            .unwrap_or((l.len(), ch))
                            .0)
-                 } else {
-                     None
                  }
              })
              .min()
@@ -399,7 +399,7 @@ fn trim_multiline_inner(s: Cow<str>, ignore_first: bool, ch: char) -> Cow<str> {
         Cow::Owned(s.lines()
                     .enumerate()
                     .map(|(i, l)| {
-                        if (ignore_first && i == 0) || l.len() == 0 {
+                        if (ignore_first && i == 0) || l.is_empty() {
                             l
                         } else {
                             l.split_at(x).1
diff --git a/tests/compile-fail/len_zero.rs b/tests/compile-fail/len_zero.rs
index 9814a1c2d7d..5168f80b856 100644
--- a/tests/compile-fail/len_zero.rs
+++ b/tests/compile-fail/len_zero.rs
@@ -76,6 +76,12 @@ fn main() {
         println!("This should not happen!");
     }
 
+    if "".len() == 0 {
+        //~^ERROR length comparison to zero
+        //~|HELP consider using `is_empty`
+        //~|SUGGESTION "".is_empty()
+    }
+
     let y = One;
     if y.len()  == 0 { //no error because One does not have .is_empty()
         println!("This should not happen either!");
diff --git a/tests/compile-fail/panic.rs b/tests/compile-fail/panic.rs
index 36427f4330b..38fe5aa2c0f 100644
--- a/tests/compile-fail/panic.rs
+++ b/tests/compile-fail/panic.rs
@@ -4,10 +4,14 @@
 #[deny(panic_params)]
 
 fn missing() {
-    panic!("{}"); //~ERROR: You probably are missing some parameter
+    if true {
+        panic!("{}"); //~ERROR: You probably are missing some parameter
+    } else {
+        panic!("{:?}"); //~ERROR: You probably are missing some parameter
+    }
 }
 
-fn ok_sigle() {
+fn ok_single() {
     panic!("foo bar");
 }
 
@@ -15,8 +19,18 @@ fn ok_multiple() {
     panic!("{}", "This is {ok}");
 }
 
+fn ok_bracket() {
+    // the match is just here because of #759, it serves no other purpose for the lint
+    match 42 {
+        1337 => panic!("{so is this"),
+        666 => panic!("so is this}"),
+        _ => panic!("}so is that{"),
+    }
+}
+
 fn main() {
     missing();
-    ok_sigle();
+    ok_single();
     ok_multiple();
+    ok_bracket();
 }