diff --git a/include/boost/decimal/detail/io.hpp b/include/boost/decimal/detail/io.hpp
index e1e4ab9be..1689ade96 100644
--- a/include/boost/decimal/detail/io.hpp
+++ b/include/boost/decimal/detail/io.hpp
@@ -127,7 +127,7 @@ auto operator<<(std::basic_ostream<charT, traits>& os, const DecimalType& d)
 
     if (BOOST_DECIMAL_UNLIKELY(!r))
     {
-        errno = static_cast<int>(r.ec);
+        errno = static_cast<int>(r.ec); // LCOV_EXCL_LINE
     }
 
     *r.ptr = '\0';
diff --git a/test/compare_dec128_and_fast.cpp b/test/compare_dec128_and_fast.cpp
index d07d1b063..cda559ada 100644
--- a/test/compare_dec128_and_fast.cpp
+++ b/test/compare_dec128_and_fast.cpp
@@ -74,7 +74,7 @@ void test_add()
 
             std::cerr << strm.str() << std::endl;
             // LCOV_EXCL_STOP
-        }
+        } // LCOV_EXCL_LINE
     }
 
     std::uniform_real_distribution<double> small_vals(0.0, 1.0);
@@ -109,7 +109,7 @@ void test_add()
 
             std::cerr << strm.str() << std::endl;
             // LCOV_EXCL_STOP
-        }
+        } // LCOV_EXCL_LINE
     }
 }
 
@@ -147,7 +147,7 @@ void test_sub()
 
             std::cerr << strm.str() << std::endl;
             // LCOV_EXCL_STOP
-        }
+        } // LCOV_EXCL_LINE
     }
 
     std::uniform_real_distribution<double> small_vals(0.0, 1.0);
@@ -182,7 +182,7 @@ void test_sub()
 
             std::cerr << strm.str() << std::endl;
             // LCOV_EXCL_STOP
-        }
+        } // LCOV_EXCL_LINE
     }
 }
 
diff --git a/test/random_decimal128_math.cpp b/test/random_decimal128_math.cpp
index 29d459768..ba53beaac 100644
--- a/test/random_decimal128_math.cpp
+++ b/test/random_decimal128_math.cpp
@@ -252,7 +252,7 @@ void random_multiplication(T lower, T upper)
         if (val1 * val2 == 0)
         {
             // Integers don't have signed 0 but decimal does
-            continue;
+            continue; // LCOV_EXCL_LINE
         }
 
         if (!BOOST_TEST_EQ(res_int, val1 * val2))
diff --git a/test/test_to_chars.cpp b/test/test_to_chars.cpp
index c9b2ee4e3..a66f102ee 100644
--- a/test/test_to_chars.cpp
+++ b/test/test_to_chars.cpp
@@ -468,52 +468,54 @@ void test_buffer_overflow()
 template <typename T>
 void zero_test()
 {
+    std::uniform_real_distribution<double> dist;
+
     constexpr T val {0, 0};
 
     // General should always be the same
     for (int precision = 0; precision < 50; ++precision)
     {
-        test_value(val, "0.0e+00", chars_format::general, precision);
+        test_value(val * T{dist(rng)}, "0.0e+00", chars_format::general, precision);
     }
 
-    test_value(val, "0e+00", chars_format::scientific, 0);
-    test_value(val, "0.0e+00", chars_format::scientific, 1);
-    test_value(val, "0.00e+00", chars_format::scientific, 2);
-    test_value(val, "0.000e+00", chars_format::scientific, 3);
-    test_value(val, "0.0000e+00", chars_format::scientific, 4);
-    test_value(val, "0.00000e+00", chars_format::scientific, 5);
-    test_value(val, "0.000000e+00", chars_format::scientific, 6);
-    test_value(val, "0.0000000e+00", chars_format::scientific, 7);
-    test_value(val, "0.00000000e+00", chars_format::scientific, 8);
-    test_value(val, "0.000000000e+00", chars_format::scientific, 9);
-    test_value(val, "0.0000000000e+00", chars_format::scientific, 10);
-    test_value(val, "0.00000000000000000000000000000000000000000000000000e+00", chars_format::scientific, 50);
-
-    test_value(val, "0p+00", chars_format::hex, 0);
-    test_value(val, "0.0p+00", chars_format::hex, 1);
-    test_value(val, "0.00p+00", chars_format::hex, 2);
-    test_value(val, "0.000p+00", chars_format::hex, 3);
-    test_value(val, "0.0000p+00", chars_format::hex, 4);
-    test_value(val, "0.00000p+00", chars_format::hex, 5);
-    test_value(val, "0.000000p+00", chars_format::hex, 6);
-    test_value(val, "0.0000000p+00", chars_format::hex, 7);
-    test_value(val, "0.00000000p+00", chars_format::hex, 8);
-    test_value(val, "0.000000000p+00", chars_format::hex, 9);
-    test_value(val, "0.0000000000p+00", chars_format::hex, 10);
-    test_value(val, "0.00000000000000000000000000000000000000000000000000p+00", chars_format::hex, 50);
-
-    test_value(val, "0", chars_format::fixed, 0);
-    test_value(val, "0.0", chars_format::fixed, 1);
-    test_value(val, "0.00", chars_format::fixed, 2);
-    test_value(val, "0.000", chars_format::fixed, 3);
-    test_value(val, "0.0000", chars_format::fixed, 4);
-    test_value(val, "0.00000", chars_format::fixed, 5);
-    test_value(val, "0.000000", chars_format::fixed, 6);
-    test_value(val, "0.0000000", chars_format::fixed, 7);
-    test_value(val, "0.00000000", chars_format::fixed, 8);
-    test_value(val, "0.000000000", chars_format::fixed, 9);
-    test_value(val, "0.0000000000", chars_format::fixed, 10);
-    test_value(val, "0.00000000000000000000000000000000000000000000000000", chars_format::fixed, 50);
+    test_value(val * T{dist(rng)}, "0e+00", chars_format::scientific, 0);
+    test_value(val * T{dist(rng)}, "0.0e+00", chars_format::scientific, 1);
+    test_value(val * T{dist(rng)}, "0.00e+00", chars_format::scientific, 2);
+    test_value(val * T{dist(rng)}, "0.000e+00", chars_format::scientific, 3);
+    test_value(val * T{dist(rng)}, "0.0000e+00", chars_format::scientific, 4);
+    test_value(val * T{dist(rng)}, "0.00000e+00", chars_format::scientific, 5);
+    test_value(val * T{dist(rng)}, "0.000000e+00", chars_format::scientific, 6);
+    test_value(val * T{dist(rng)}, "0.0000000e+00", chars_format::scientific, 7);
+    test_value(val * T{dist(rng)}, "0.00000000e+00", chars_format::scientific, 8);
+    test_value(val * T{dist(rng)}, "0.000000000e+00", chars_format::scientific, 9);
+    test_value(val * T{dist(rng)}, "0.0000000000e+00", chars_format::scientific, 10);
+    test_value(val * T{dist(rng)}, "0.00000000000000000000000000000000000000000000000000e+00", chars_format::scientific, 50);
+
+    test_value(val * T{dist(rng)}, "0p+00", chars_format::hex, 0);
+    test_value(val * T{dist(rng)}, "0.0p+00", chars_format::hex, 1);
+    test_value(val * T{dist(rng)}, "0.00p+00", chars_format::hex, 2);
+    test_value(val * T{dist(rng)}, "0.000p+00", chars_format::hex, 3);
+    test_value(val * T{dist(rng)}, "0.0000p+00", chars_format::hex, 4);
+    test_value(val * T{dist(rng)}, "0.00000p+00", chars_format::hex, 5);
+    test_value(val * T{dist(rng)}, "0.000000p+00", chars_format::hex, 6);
+    test_value(val * T{dist(rng)}, "0.0000000p+00", chars_format::hex, 7);
+    test_value(val * T{dist(rng)}, "0.00000000p+00", chars_format::hex, 8);
+    test_value(val * T{dist(rng)}, "0.000000000p+00", chars_format::hex, 9);
+    test_value(val * T{dist(rng)}, "0.0000000000p+00", chars_format::hex, 10);
+    test_value(val * T{dist(rng)}, "0.00000000000000000000000000000000000000000000000000p+00", chars_format::hex, 50);
+
+    test_value(val * T{dist(rng)}, "0", chars_format::fixed, 0);
+    test_value(val * T{dist(rng)}, "0.0", chars_format::fixed, 1);
+    test_value(val * T{dist(rng)}, "0.00", chars_format::fixed, 2);
+    test_value(val * T{dist(rng)}, "0.000", chars_format::fixed, 3);
+    test_value(val * T{dist(rng)}, "0.0000", chars_format::fixed, 4);
+    test_value(val * T{dist(rng)}, "0.00000", chars_format::fixed, 5);
+    test_value(val * T{dist(rng)}, "0.000000", chars_format::fixed, 6);
+    test_value(val * T{dist(rng)}, "0.0000000", chars_format::fixed, 7);
+    test_value(val * T{dist(rng)}, "0.00000000", chars_format::fixed, 8);
+    test_value(val * T{dist(rng)}, "0.000000000", chars_format::fixed, 9);
+    test_value(val * T{dist(rng)}, "0.0000000000", chars_format::fixed, 10);
+    test_value(val * T{dist(rng)}, "0.00000000000000000000000000000000000000000000000000", chars_format::fixed, 50);
 }
 
 // See: https://github.com/cppalliance/decimal/issues/434