diff --git a/Cargo.toml b/Cargo.toml
index e9e01e5..a75cfbb 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -15,6 +15,8 @@ wasmi-validation = { version = "0.1", path = "validation", default-features = fa
 parity-wasm = { version = "0.31", default-features = false }
 memory_units = "0.3.0"
 libm = { version = "0.1.2", optional = true }
+num-rational = "0.2.2"
+num-traits = "0.2.8"
 
 [dev-dependencies]
 assert_matches = "1.1"
@@ -27,6 +29,8 @@ default = ["std"]
 std = [
     "parity-wasm/std",
     "wasmi-validation/std",
+    "num-rational/std",
+    "num-traits/std"
 ]
 # Enable for no_std support
 core = [
diff --git a/src/lib.rs b/src/lib.rs
index ccbc90a..9384147 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -128,6 +128,9 @@ use std::error;
 #[cfg(not(feature = "std"))]
 extern crate libm;
 
+extern crate num_rational;
+extern crate num_traits;
+
 /// Error type which can be thrown by wasm code or by host environment.
 ///
 /// Under some conditions, wasm execution may produce a `Trap`, which immediately aborts execution.
diff --git a/src/value.rs b/src/value.rs
index 9891923..8d5061a 100644
--- a/src/value.rs
+++ b/src/value.rs
@@ -366,27 +366,18 @@ impl WrapInto<F32> for F64 {
 }
 
 macro_rules! impl_try_truncate_into {
-    ($from: ident, $into: ident) => {
+    (@primitive $from: ident, $into: ident, $to_primitive:path) => {
         impl TryTruncateInto<$into, TrapKind> for $from {
             fn try_truncate_into(self) -> Result<$into, TrapKind> {
                 // Casting from a float to an integer will round the float towards zero
-                // NOTE: currently this will cause Undefined Behavior if the rounded value cannot be represented by the
-                // target integer type. This includes Inf and NaN. This is a bug and will be fixed.
-                if self.is_nan() || self.is_infinite() {
-                    return Err(TrapKind::InvalidConversionToInt);
-                }
-
-                // range check
-                let result = self as $into;
-                if result as $from != self.trunc() {
-                    return Err(TrapKind::InvalidConversionToInt);
-                }
-
-                Ok(self as $into)
+                num_rational::BigRational::from_float(self)
+                    .map(|val| val.to_integer())
+                    .and_then(|val| $to_primitive(&val))
+                    .ok_or(TrapKind::InvalidConversionToInt)
             }
         }
     };
-    ($from:ident, $intermediate:ident, $into:ident) => {
+    (@wrapped $from:ident, $intermediate:ident, $into:ident) => {
         impl TryTruncateInto<$into, TrapKind> for $from {
             fn try_truncate_into(self) -> Result<$into, TrapKind> {
                 $intermediate::from(self).try_truncate_into()
@@ -395,22 +386,22 @@ macro_rules! impl_try_truncate_into {
     };
 }
 
-impl_try_truncate_into!(f32, i32);
-impl_try_truncate_into!(f32, i64);
-impl_try_truncate_into!(f64, i32);
-impl_try_truncate_into!(f64, i64);
-impl_try_truncate_into!(f32, u32);
-impl_try_truncate_into!(f32, u64);
-impl_try_truncate_into!(f64, u32);
-impl_try_truncate_into!(f64, u64);
-impl_try_truncate_into!(F32, f32, i32);
-impl_try_truncate_into!(F32, f32, i64);
-impl_try_truncate_into!(F64, f64, i32);
-impl_try_truncate_into!(F64, f64, i64);
-impl_try_truncate_into!(F32, f32, u32);
-impl_try_truncate_into!(F32, f32, u64);
-impl_try_truncate_into!(F64, f64, u32);
-impl_try_truncate_into!(F64, f64, u64);
+impl_try_truncate_into!(@primitive f32, i32, num_traits::cast::ToPrimitive::to_i32);
+impl_try_truncate_into!(@primitive f32, i64, num_traits::cast::ToPrimitive::to_i64);
+impl_try_truncate_into!(@primitive f64, i32, num_traits::cast::ToPrimitive::to_i32);
+impl_try_truncate_into!(@primitive f64, i64, num_traits::cast::ToPrimitive::to_i64);
+impl_try_truncate_into!(@primitive f32, u32, num_traits::cast::ToPrimitive::to_u32);
+impl_try_truncate_into!(@primitive f32, u64, num_traits::cast::ToPrimitive::to_u64);
+impl_try_truncate_into!(@primitive f64, u32, num_traits::cast::ToPrimitive::to_u32);
+impl_try_truncate_into!(@primitive f64, u64, num_traits::cast::ToPrimitive::to_u64);
+impl_try_truncate_into!(@wrapped F32, f32, i32);
+impl_try_truncate_into!(@wrapped F32, f32, i64);
+impl_try_truncate_into!(@wrapped F64, f64, i32);
+impl_try_truncate_into!(@wrapped F64, f64, i64);
+impl_try_truncate_into!(@wrapped F32, f32, u32);
+impl_try_truncate_into!(@wrapped F32, f32, u64);
+impl_try_truncate_into!(@wrapped F64, f64, u32);
+impl_try_truncate_into!(@wrapped F64, f64, u64);
 
 macro_rules! impl_extend_into {
     ($from:ident, $into:ident) => {
diff --git a/test.sh b/test.sh
index ce9aa56..2240728 100755
--- a/test.sh
+++ b/test.sh
@@ -5,7 +5,11 @@ set -eux
 EXTRA_ARGS=""
 
 if [ -n "${TARGET-}" ]; then
-    EXTRA_ARGS="--target=${TARGET} -- --test-threads=1"
+    # Tests build in debug mode are prohibitively
+    # slow when ran under emulation so that
+    # e.g. Travis CI will hit timeouts.
+    EXTRA_ARGS="--release --target=${TARGET}"
+    export RUSTFLAGS="--cfg debug_assertions"
 fi
 
 cd $(dirname $0)