diff --git a/include/sled/log/log.h b/include/sled/log/log.h
index d83f4ed..f31641c 100644
--- a/include/sled/log/log.h
+++ b/include/sled/log/log.h
@@ -56,8 +56,8 @@ void Log(LogLevel level,
 
 #define SLOG_ASSERT(cond, tag, fmt, ...)                                       \
     do {                                                                       \
-        if (!(cond)) {                                                         \
-            SLOG(sled::LogLevel::kFatal, __VA_ARGS__);                         \
+        if (!!(cond)) {                                                        \
+            SLOG(sled::LogLevel::kFatal, tag, fmt, ##__VA_ARGS__);             \
             assert(cond);                                                      \
         }                                                                      \
     } while (0)
@@ -87,6 +87,6 @@ void Log(LogLevel level,
 #define LOGF(tag, fmt, ...)                                                    \
     SLOG(sled::LogLevel::kFatal, tag, fmt, ##__VA_ARGS__)
 
-#define ASSERT(cond, fmt, ...) SLOG_ASSERT(cond, "ASSERT", fmt, ##__VA_ARGS__);
+#define ASSERT(cond, fmt, ...) SLOG_ASSERT(cond, "ASSERT", fmt, ##__VA_ARGS__)
 
 #endif// LOG_H
diff --git a/include/sled/numerics/fixed_point_number.h b/include/sled/numerics/fixed_point_number.h
new file mode 100644
index 0000000..fdc3238
--- /dev/null
+++ b/include/sled/numerics/fixed_point_number.h
@@ -0,0 +1,708 @@
+/*
+The MIT License (MIT)
+
+Copyright (c) 2015 Julius Ikkala
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+*/
+#ifndef FIXED_POINT_H_
+#define FIXED_POINT_H_
+#include <Eigen/Eigen>
+#include <cmath>
+#include <cstdint>
+#include <fmt/ostream.h>
+#include <type_traits>
+
+//==========================================================================
+//Fixed-point numbers
+//==========================================================================
+namespace fp {
+/*The fixed-point number class. f is the amount of fractional bits, I is
+          the internal type. If I is signed, q will be signed.*/
+template<unsigned f, typename I>
+struct q {
+    I i;
+
+    q(int i = 0); /*Integer literals are int*/
+    q(unsigned u);
+    q(uintmax_t s);
+    q(double d);
+    q(long double d);
+    template<unsigned fb>
+    q(q<fb, I> a);
+
+    operator int() const;
+    operator float() const;
+    operator double() const;
+    operator long double() const;
+    template<unsigned fb>
+    q<f, I> operator+(q<fb, I> b) const;
+    template<unsigned fb>
+    q<f, I> operator-(q<fb, I> b) const;
+    template<unsigned fb>
+    q<f, I> operator*(q<fb, I> b) const;
+    template<unsigned fb>
+    q<f, I> operator/(q<fb, I> b) const;
+    template<unsigned fb>
+    q<f, I> operator%(q<fb, I> b) const;
+
+    template<typename T>
+    q<f, I> operator+(T b) const;
+    template<typename T>
+    q<f, I> operator-(T b) const;
+    template<typename T>
+    q<f, I> operator*(T b) const;
+    template<typename T>
+    q<f, I> operator/(T b) const;
+    template<typename T>
+    q<f, I> operator%(T b) const;
+
+    template<typename T>
+    q<f, I> &operator+=(T b);
+    template<typename T>
+    q<f, I> &operator-=(T b);
+    template<typename T>
+    q<f, I> &operator*=(T b);
+    template<typename T>
+    q<f, I> &operator/=(T b);
+    template<typename T>
+    q<f, I> &operator%=(T b);
+
+    q<f, I> operator-() const;
+
+    template<unsigned fb>
+    q<f, I> &operator=(q<fb, I> b);
+    q<f, I> &operator=(int b);
+    q<f, I> &operator=(double b);
+    q<f, I> &operator=(long double b);
+
+    template<unsigned fb>
+    bool operator>=(q<fb, I> b) const;
+    template<unsigned fb>
+    bool operator>(q<fb, I> b) const;
+    template<unsigned fb>
+    bool operator<=(q<fb, I> b) const;
+    template<unsigned fb>
+    bool operator<(q<fb, I> b) const;
+    template<unsigned fb>
+    bool operator==(q<fb, I> b) const;
+    template<unsigned fb>
+    bool operator!=(q<fb, I> b) const;
+
+    friend std::ostream &operator<<(std::ostream &os, const q<f, I> &fp)
+    {
+        os << (float) fp;
+        return os;
+    }
+
+    friend std::istream &operator>>(std::istream &is, q<f, I> &fp)
+    {
+        float val;
+        is >> val;
+        fp = val;
+        return is;
+    }
+};
+
+typedef q<16, uint32_t> UQ16_16;
+typedef q<32, uint64_t> UQ32_32;
+typedef q<16, uint64_t> UQ48_16;
+typedef q<16, int32_t> Q16_16;
+typedef q<32, int64_t> Q32_32;
+typedef q<16, int64_t> Q48_16;
+
+/*Returns the absolute value of x*/
+template<unsigned f, typename I>
+q<f, I> abs(q<f, I> x);
+}// namespace fp
+
+//==========================================================================
+//Internal helper functions and classes
+//==========================================================================
+namespace fp_internal {
+/*Count leading zeroes*/
+template<typename T>
+unsigned
+clz(T x)
+{
+    unsigned i = 0;
+    while (!(x & (((T) 1) << (sizeof(T) * 8 - 1))) && (x <<= 1)) ++i;
+    return i;
+}
+
+/*Used to select the correct shift operator in compile-time*/
+template<int shift, bool rsh, bool zero, typename T>
+struct shifter {
+    static T op(T x);
+};
+
+template<int shift, typename T>
+struct shifter<shift, true, false, T> {
+    static T op(T x) { return x >> shift; };
+};
+
+template<int shift, typename T>
+struct shifter<shift, false, false, T> {
+    static T op(T x) { return x << -shift; };
+};
+
+template<int shift, bool rsh, typename T>
+struct shifter<shift, rsh, true, T> {
+    static T op(T x) { return 0; };
+};
+
+template<typename T>
+constexpr T
+abs_helper(const T x) noexcept
+{
+    return (// deal with signed-zeros
+        x == T(0) ? T(0) :
+                  // else
+            x < T(0) ? -x
+                     : x);
+}
+
+/*Signed right shift. Accepts negative values of shift and never
+          complains about too big shifts. Compile-time version.*/
+template<int shift, typename T>
+constexpr T
+signed_rsh(T x)
+{
+    return shifter<shift, (shift >= 0), (abs_helper(shift) >= sizeof(T) * 8),
+                   T>::op(x);
+}
+
+/*Signed right shift, run time version.*/
+template<typename T>
+T
+signed_rsh(T x, int shift)
+{
+    return std::abs(shift) < sizeof(T) * 8
+        ? (shift < 0 ? x << -shift : x >> shift)
+        : 0;
+}
+
+/*Signed left shift, compile-time version*/
+template<int shift, typename T>
+T
+signed_lsh(T x)
+{
+    return signed_rsh<-shift, T>(x);
+}
+
+/*Signed left shift, run time version*/
+template<typename T>
+T
+signed_lsh(T x, int shift)
+{
+    return std::abs(shift) < sizeof(T) * 8
+        ? (shift < 0 ? x >> -shift : x << shift)
+        : 0;
+}
+
+/*Multiplies and simultaneously right-shifts the argument values,
+          without losing the high bits. Compile-time version*/
+template<int shift, typename T>
+T
+mul_rsh(T a, T b)
+{
+    typedef typename std::make_unsigned<T>::type U;
+    static const int bits = sizeof(T) * 8;
+    static const int halfbits = sizeof(T) * 4;
+    static const U lowmask = (((T) 1) << (halfbits)) - 1;
+    static const U highmask = lowmask << (halfbits);
+    T a1 = a >> (halfbits);
+    T a2 = a - (a & highmask);
+    T b1 = b >> (halfbits);
+    T b2 = b - (b & highmask);
+    T a1b1 = a1 * b1;
+    T a1b2 = a1 * b2;
+    T a2b1 = a2 * b1;
+    T a2b2 = a2 * b2;
+    U high = a1b1 + (a2b1 >> (halfbits)) + (a1b2 >> (halfbits));
+
+    U low = a2b2;
+    high += (low += (a2b1 << halfbits)) < a2b2;
+    U tmp = low;
+    high += (low += (a1b2 << halfbits)) < tmp;
+    low = signed_rsh<shift>(low);
+    low += signed_lsh<bits - shift>(high);
+    return low;
+}
+
+/*Run time version*/
+template<typename T>
+T
+mul_rsh(T a, T b, int shift)
+{
+    typedef typename std::make_unsigned<T>::type U;
+    static const int bits = sizeof(T) * 8;
+    static const int halfbits = sizeof(T) * 4;
+    static const U lowmask = (((T) 1) << (halfbits)) - 1;
+    static const U highmask = lowmask << (halfbits);
+    T a1 = a >> (halfbits);
+    T a2 = a - (a & highmask);
+    T b1 = b >> (halfbits);
+    T b2 = b - (b & highmask);
+    T a1b1 = a1 * b1;
+    T a1b2 = a1 * b2;
+    T a2b1 = a2 * b1;
+    T a2b2 = a2 * b2;
+    U high = a1b1 + (a2b1 >> (halfbits)) + (a1b2 >> (halfbits));
+
+    U low = a2b2;
+    high += (low += (a2b1 << halfbits)) < a2b2;
+    U tmp = low;
+    high += (low += (a1b2 << halfbits)) < tmp;
+    low = signed_rsh(low, shift);
+    low += signed_lsh(high, bits - shift);
+    return low;
+}
+}// namespace fp_internal
+
+//==========================================================================
+//Implementation
+//==========================================================================
+template<unsigned f, typename I>
+fp::q<f, I>::q(int u)
+{
+    i = fp_internal::signed_lsh<f>((I) u);
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>::q(unsigned u)
+{
+    i = fp_internal::signed_lsh<f>((I) u);
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>::q(uintmax_t s)
+{
+    i = fp_internal::signed_lsh<f>((I) s);
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>::q(double d)
+{
+    int exp = 0;
+    double tmp = frexp(d, &exp);
+    i = lroundl(ldexp(tmp, exp + f));
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>::q(long double d)
+{
+    int exp = 0;
+    long double tmp = frexp(d, &exp);
+    i = llroundl(ldexp(tmp, exp + f));
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+fp::q<f, I>::q(q<fb, I> a)
+{
+    i = fp_internal::signed_rsh<fb - f>(a.i);
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>::operator int() const
+{
+    return fp_internal::signed_rsh<f>(i);
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>::operator float() const
+{
+    return ldexpf((float) i, -(int) f);
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>::operator double() const
+{
+    return ldexp((double) i, -(int) f);
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>::operator long double() const
+{
+    return ldexp((long double) i, -(int) f);
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+fp::q<f, I>
+fp::q<f, I>::operator+(q<fb, I> b) const
+{
+    q<f, I> t;
+    t.i = i + fp_internal::signed_rsh<fb - f>(b.i);
+    return t;
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+fp::q<f, I>
+fp::q<f, I>::operator-(q<fb, I> b) const
+{
+    q<f, I> t;
+    t.i = i - fp_internal::signed_rsh<fb - f>(b.i);
+    return t;
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+fp::q<f, I>
+fp::q<f, I>::operator*(q<fb, I> b) const
+{
+    q<f, I> t;
+    t.i = fp_internal::mul_rsh<fb>(i, b.i);
+    return t;
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+fp::q<f, I>
+fp::q<f, I>::operator/(q<fb, I> b) const
+{
+    static const I msb = (I) 1
+        << (sizeof(I) * 8 - 1);//Most significant bit for the type
+    //Make b positive so that leading zeroes can be properly computed
+    I abs_b = b.i < 0 ? -b.i : b.i;
+    unsigned lz = fp_internal::clz(abs_b);//Amount of leading zeroes
+    //normalize b to [0.5, 1.0[, where all digits are after radix
+    I d = (abs_b << lz);
+    q<sizeof(I) * 8 + 1, typename std::make_unsigned<I>::type> e;
+    e.i = (~d + 1) << 1;//[0, 0.5[
+    //r is the reciprocal of d
+    q<sizeof(I) * 8 - 1, typename std::make_unsigned<I>::type> r(1);
+    for (unsigned i = 0; i < sizeof(I) - 1; ++i) {
+        r = r + r * e;
+        e = e * e;
+    }
+    q<f, I> t;
+    t.i = (I) fp_internal::mul_rsh(//adjust the radix point of (this*r)
+        r.i,
+        (typename std::make_unsigned<I>::type)(this->i < 0 ? -this->i
+                                                           : this->i),
+        sizeof(i) * 16 - fb - lz - (d == msb) - 1);
+    t.i = (b.i < 0) ^ (this->i < 0) ? -t.i : t.i;//set correct sign
+    return t;
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+fp::q<f, I>
+fp::q<f, I>::operator%(q<fb, I> b) const
+{
+    q<f, I> t;
+    t.i = i % fp_internal::signed_rsh<fb - f>(b.i);
+    return t;
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I>
+fp::q<f, I>::operator+(T b) const
+{
+    return *this + q<f, I>(b);
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I>
+fp::q<f, I>::operator-(T b) const
+{
+    return *this - q<f, I>(b);
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I>
+fp::q<f, I>::operator*(T b) const
+{
+    return *this * q<f, I>(b);
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I>
+fp::q<f, I>::operator/(T b) const
+{
+    return *this / q<f, I>(b);
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I>
+fp::q<f, I>::operator%(T b) const
+{
+    return *this % q<f, I>(b);
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I> &
+fp::q<f, I>::operator+=(T b)
+{
+    return *this = *this + b;
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I> &
+fp::q<f, I>::operator-=(T b)
+{
+    return *this = *this - b;
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I> &
+fp::q<f, I>::operator*=(T b)
+{
+    return *this = *this * b;
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I> &
+fp::q<f, I>::operator/=(T b)
+{
+    return *this = *this / b;
+}
+
+template<unsigned f, typename I>
+template<typename T>
+fp::q<f, I> &
+fp::q<f, I>::operator%=(T b)
+{
+    return *this = *this % b;
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>
+fp::q<f, I>::operator-() const
+{
+    q<f, I> t;
+    t.i = -i;
+    return t;
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+fp::q<f, I> &
+fp::q<f, I>::operator=(q<fb, I> b)
+{
+    i = fp_internal::signed_rsh<fb - f>(b.i);
+    return *this;
+}
+
+template<unsigned f, typename I>
+fp::q<f, I> &
+fp::q<f, I>::operator=(int b)
+{
+    i = fp_internal::signed_lsh<f>((I) b);
+    return *this;
+}
+
+template<unsigned f, typename I>
+fp::q<f, I> &
+fp::q<f, I>::operator=(double b)
+{
+    int exp = 0;
+    double tmp = frexp(b, &exp);
+    i = llroundl(ldexp(tmp, exp + f));
+    return *this;
+}
+
+template<unsigned f, typename I>
+fp::q<f, I> &
+fp::q<f, I>::operator=(long double b)
+{
+    int exp = 0;
+    long double tmp = frexp(b, &exp);
+    i = llroundl(ldexp(tmp, exp + f));
+    return *this;
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+bool
+fp::q<f, I>::operator>=(q<fb, I> b) const
+{
+    static const unsigned bits = sizeof(I) * 8;
+    I ma = fp_internal::signed_rsh<f>(i);
+    I mb = fp_internal::signed_rsh<fb>(b.i);
+    return (ma > mb)
+        || ((ma == mb)
+            && ((typename std::make_unsigned<I>::type)
+                    fp_internal::signed_lsh<bits - f>(i)
+                >= (typename std::make_unsigned<I>::type)
+                    fp_internal::signed_lsh<bits - fb>(b.i)));
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+bool
+fp::q<f, I>::operator>(q<fb, I> b) const
+{
+    static const unsigned bits = sizeof(I) * 8;
+    I ma = fp_internal::signed_rsh<f>(i);
+    I mb = fp_internal::signed_rsh<fb>(b.i);
+    return (ma > mb)
+        || ((ma == mb)
+            && ((typename std::make_unsigned<I>::type)
+                    fp_internal::signed_lsh<bits - f>(i)
+                > (typename std::make_unsigned<I>::type)
+                    fp_internal::signed_lsh<bits - fb>(b.i)));
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+bool
+fp::q<f, I>::operator<=(q<fb, I> b) const
+{
+    static const unsigned bits = sizeof(I) * 8;
+    I ma = fp_internal::signed_rsh<f>(i);
+    I mb = fp_internal::signed_rsh<fb>(b.i);
+    return (ma < mb)
+        || ((ma == mb)
+            && ((typename std::make_unsigned<I>::type)
+                    fp_internal::signed_lsh<bits - f>(i)
+                <= (typename std::make_unsigned<I>::type)
+                    fp_internal::signed_lsh<bits - fb>(b.i)));
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+bool
+fp::q<f, I>::operator<(q<fb, I> b) const
+{
+    static const unsigned bits = sizeof(I) * 8;
+    I ma = fp_internal::signed_rsh<f>(i);
+    I mb = fp_internal::signed_rsh<fb>(b.i);
+    return (ma < mb)
+        || ((ma == mb)
+            && ((typename std::make_unsigned<I>::type)
+                    fp_internal::signed_lsh<bits - f>(i)
+                < (typename std::make_unsigned<I>::type)
+                    fp_internal::signed_lsh<bits - fb>(b.i)));
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+bool
+fp::q<f, I>::operator==(q<fb, I> b) const
+{
+    return fp_internal::signed_rsh<f - fb>(i) == b.i
+        && fp_internal::signed_rsh<fb - f>(b.i) == i;
+}
+
+template<unsigned f, typename I>
+template<unsigned fb>
+bool
+fp::q<f, I>::operator!=(q<fb, I> b) const
+{
+    return fp_internal::signed_rsh<f - fb>(i) != b.i
+        || fp_internal::signed_rsh<fb - f>(b.i) != i;
+}
+
+template<unsigned f, typename I>
+fp::q<f, I>
+fp::abs(q<f, I> x)
+{
+    return (x.i >= 0 ? x : -x);
+}
+
+namespace sled {
+template<unsigned bits, typename T>
+using FixedPoint = fp::q<bits, T>;
+
+using FixedFloat = fp::Q32_32;
+
+template<unsigned bits, typename T>
+inline const FixedPoint<bits, T>
+conj(const FixedPoint<bits, T> &val)
+{
+    return val;
+}
+
+template<unsigned bits, typename T>
+inline const FixedPoint<bits, T>
+real(const FixedPoint<bits, T> &val)
+{
+    return val;
+}
+
+template<unsigned bits, typename T>
+inline const FixedPoint<bits, T>
+imag(const FixedPoint<bits, T> &val)
+{
+    return 0.;
+}
+
+template<unsigned bits, typename T>
+inline const FixedPoint<bits, T>
+abs(const FixedPoint<bits, T> &val)
+{
+    return fp::abs(val);
+}
+
+template<unsigned bits, typename T>
+inline const FixedPoint<bits, T>
+abs2(const FixedPoint<bits, T> &val)
+{
+    return val * val;
+}
+
+}// namespace sled
+
+template<unsigned bits, typename T>
+struct fmt::formatter<sled::FixedPoint<bits, T>> : ostream_formatter {};
+
+namespace Eigen {
+template<unsigned bits, typename T>
+struct NumTraits<sled::FixedPoint<bits, T>> : NumTraits<float> {
+    typedef sled::FixedPoint<bits, T> Real;
+    typedef sled::FixedPoint<bits, T> NonInteger;
+    typedef sled::FixedPoint<bits, T> Nested;
+
+    enum {
+        IsComplex = 0,
+        IsInteger = 0,
+        IsSigned = std::is_signed<T>::value,
+        RequireInitialization = 1,
+        ReadCost = 1,
+        AddCost = 3,
+        MulCost = 3
+    };
+};
+
+template<typename BinaryOp, unsigned bits, typename T>
+struct ScalarBinaryOpTraits<sled::FixedPoint<bits, T>, float, BinaryOp> {
+    typedef sled::FixedPoint<bits, T> ReturnType;
+};
+
+template<typename BinaryOp, unsigned bits, typename T>
+struct ScalarBinaryOpTraits<float, sled::FixedPoint<bits, T>, BinaryOp> {
+    typedef sled::FixedPoint<bits, T> ReturnType;
+};
+
+}// namespace Eigen
+
+#endif
diff --git a/include/sled/queue/circle_queue.h b/include/sled/queue/circle_queue.h
index 06d7f67..11eafd8 100644
--- a/include/sled/queue/circle_queue.h
+++ b/include/sled/queue/circle_queue.h
@@ -14,38 +14,38 @@ namespace sled {
 
 template<typename T, size_t LEN>
 class CircleQueue {
-    static_assert(LEN > 0, "LEN should be greater than 0");
+    static_assert(LEN > 0, "LEN should be greater than 0.");
 
 public:
     void Push(T &&val)
     {
-        ASSERT(size() < LEN, "queue is full");
+        ASSERT(size() < LEN, "queue is full.");
         queue_.get(tail_) = std::move(val);
         ++tail_;
     }
 
     void Push(const T &val)
     {
-        ASSERT(size() < LEN, "queue is full");
+        ASSERT(size() < LEN, "queue is full.");
         queue_.get(tail_) = val;
         ++tail_;
     }
 
     T &Front()
     {
-        ASSERT(!empty());
+        ASSERT(!empty(), "queue is empty.");
         return queue_.get(head_);
     }
 
     T &Back()
     {
-        ASSERT(!empty());
+        ASSERT(!empty(), "queue is empty.");
         return queue_.get((tail_ + LEN) % (LEN + 1));
     }
 
     void Pop()
     {
-        ASSERT(!empty());
+        ASSERT(!empty(), "queue is empty.");
         head_ = (head_ + 1) % (LEN + 1);
     }
 
diff --git a/include/sled/scoped_refptr.h b/include/sled/scoped_refptr.h
index c55abb4..7d2f731 100644
--- a/include/sled/scoped_refptr.h
+++ b/include/sled/scoped_refptr.h
@@ -84,6 +84,7 @@ public:
     scoped_refptr<T> &operator=(const scoped_refptr<T> &&r) noexcept
     {
         scoped_refptr<T>(std::move(r)).swap(*this);
+        return *this;
     }
 
     template<typename U>
diff --git a/src/log/log.cc b/src/log/log.cc
index 7499256..f050167 100644
--- a/src/log/log.cc
+++ b/src/log/log.cc
@@ -3,6 +3,21 @@
 #include <iostream>
 
 namespace sled {
+
+class ScopedAtomicWaiter {
+public:
+    ScopedAtomicWaiter(std::atomic_bool &flag) : flag_(flag)
+    {
+        bool old = flag_.load();
+        while (!flag_.compare_exchange_weak(old, false)) { continue; }
+    }
+
+    ~ScopedAtomicWaiter() { flag_.store(true); }
+
+private:
+    std::atomic_bool &flag_;
+};
+
 void
 Log(LogLevel level,
     const char *tag,
@@ -12,6 +27,8 @@ Log(LogLevel level,
     const char *func_name,
     ...)
 {
+    static std::atomic_bool allow(true);
+    ScopedAtomicWaiter waiter(allow);
     int len = file_name ? strlen(file_name) : 0;
     while (len > 0 && file_name[len - 1] != '/') { len--; }
 
diff --git a/src/synchronization/event.cc b/src/synchronization/event.cc
index 28e09a6..5b160cc 100644
--- a/src/synchronization/event.cc
+++ b/src/synchronization/event.cc
@@ -30,9 +30,9 @@ Event::Reset()
 bool
 Event::Wait(TimeDelta give_up_after, TimeDelta warn_after)
 {
-    MutexLock lock(&mutex_);
+    MutexLock guard(&mutex_);
     bool wait_success =
-        cv_.WaitFor(lock, give_up_after, [&] { return event_status_; });
+        cv_.WaitFor(guard, give_up_after, [&] { return event_status_; });
     if (!wait_success) { return false; }
 
     if (!is_manual_reset_) { event_status_ = false; }