diff --git a/README.md b/README.md
index 2f822ca159..51bc370eb3 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ utility or as a library embedded in a larger application.
 
 [![Build Status](https://dev.azure.com/CraneStation/Wasmtime/_apis/build/status/CraneStation.wasmtime?branchName=master)](https://dev.azure.com/CraneStation/Wasmtime/_build/latest?definitionId=4&branchName=master)
 [![Gitter chat](https://badges.gitter.im/CraneStation/CraneStation.svg)](https://gitter.im/CraneStation/Lobby)
-![Minimum rustc 1.36](https://img.shields.io/badge/rustc-1.36+-green.svg)
+![Minimum rustc 1.37](https://img.shields.io/badge/rustc-1.37+-green.svg)
 
 Wasmtime passes the WebAssembly spec testsuite, and supports a new system
 API proposal called [WebAssembly System Interface], or WASI.
diff --git a/wasmtime-debug/src/write_debuginfo.rs b/wasmtime-debug/src/write_debuginfo.rs
index 6920472c3b..48b6b6a2d3 100644
--- a/wasmtime-debug/src/write_debuginfo.rs
+++ b/wasmtime-debug/src/write_debuginfo.rs
@@ -25,7 +25,7 @@ pub trait SymbolResolver {
 pub fn emit_dwarf(
     artifact: &mut Artifact,
     mut dwarf: Dwarf,
-    symbol_resolver: &SymbolResolver,
+    symbol_resolver: &dyn SymbolResolver,
 ) -> result::Result<(), failure::Error> {
     let endian = RunTimeEndian::Little;
 
@@ -61,11 +61,11 @@ pub fn emit_dwarf(
 pub struct WriterRelocate<'a> {
     relocs: Vec<DebugReloc>,
     writer: EndianVec<RunTimeEndian>,
-    symbol_resolver: &'a SymbolResolver,
+    symbol_resolver: &'a dyn SymbolResolver,
 }
 
 impl<'a> WriterRelocate<'a> {
-    pub fn new(endian: RunTimeEndian, symbol_resolver: &'a SymbolResolver) -> Self {
+    pub fn new(endian: RunTimeEndian, symbol_resolver: &'a dyn SymbolResolver) -> Self {
         WriterRelocate {
             relocs: Vec::new(),
             writer: EndianVec::new(endian),
diff --git a/wasmtime-environ/src/cranelift.rs b/wasmtime-environ/src/cranelift.rs
index 7017fd341a..c2a182abd3 100644
--- a/wasmtime-environ/src/cranelift.rs
+++ b/wasmtime-environ/src/cranelift.rs
@@ -96,7 +96,7 @@ fn get_function_address_map<'data>(
     context: &Context,
     data: &FunctionBodyData<'data>,
     body_len: usize,
-    isa: &isa::TargetIsa,
+    isa: &dyn isa::TargetIsa,
 ) -> FunctionAddressMap {
     let mut instructions = Vec::new();
 
diff --git a/wasmtime-jit/src/context.rs b/wasmtime-jit/src/context.rs
index 0e2940d678..eabee01933 100644
--- a/wasmtime-jit/src/context.rs
+++ b/wasmtime-jit/src/context.rs
@@ -105,7 +105,7 @@ impl Context {
     }
 
     /// Construct a new instance of `Context` with the given target.
-    pub fn with_isa(isa: Box<TargetIsa>) -> Self {
+    pub fn with_isa(isa: Box<dyn TargetIsa>) -> Self {
         Self::new(Box::new(Compiler::new(isa)))
     }
 
diff --git a/wasmtime-runtime/src/instance.rs b/wasmtime-runtime/src/instance.rs
index 688e52b6f5..08131d7b8b 100644
--- a/wasmtime-runtime/src/instance.rs
+++ b/wasmtime-runtime/src/instance.rs
@@ -441,7 +441,7 @@ impl Instance {
     }
 
     /// Return a reference to the custom state attached to this instance.
-    pub fn host_state(&mut self) -> &mut Any {
+    pub fn host_state(&mut self) -> &mut dyn Any {
         &mut *self.host_state
     }
 
@@ -855,7 +855,7 @@ impl InstanceHandle {
     }
 
     /// Return a reference to the custom state attached to this instance.
-    pub fn host_state(&mut self) -> &mut Any {
+    pub fn host_state(&mut self) -> &mut dyn Any {
         self.instance_mut().host_state()
     }
 
diff --git a/wasmtime-runtime/src/vmcontext.rs b/wasmtime-runtime/src/vmcontext.rs
index b19ac8c2a9..51cec31f84 100644
--- a/wasmtime-runtime/src/vmcontext.rs
+++ b/wasmtime-runtime/src/vmcontext.rs
@@ -527,7 +527,7 @@ impl VMContext {
     ///
     /// This is unsafe because it doesn't work on just any `VMContext`, it must
     /// be a `VMContext` allocated as part of an `Instance`.
-    pub unsafe fn host_state(&mut self) -> &mut Any {
+    pub unsafe fn host_state(&mut self) -> &mut dyn Any {
         self.instance().host_state()
     }