diff --git a/base/base_tests/string_utils_test.cpp b/base/base_tests/string_utils_test.cpp
index 6bc2eed622..1a3fac8c45 100644
--- a/base/base_tests/string_utils_test.cpp
+++ b/base/base_tests/string_utils_test.cpp
@@ -254,9 +254,20 @@ UNIT_TEST(to_string_dac)
 
   TEST_EQUAL(strings::to_string_dac(-0.0039, 2), "-0", ());
   TEST_EQUAL(strings::to_string_dac(0.0039, 2), "0", ());
+  TEST_EQUAL(strings::to_string_dac(-1.0039, 2), "-1", ());
+  TEST_EQUAL(strings::to_string_dac(1.0039, 2), "1", ());
 
   TEST_EQUAL(strings::to_string_dac(0., 5), "0", ());
   TEST_EQUAL(strings::to_string_dac(0., 0), "0", ());
+
+  TEST_EQUAL(strings::to_string_dac(1.0, 6), "1", ());
+  TEST_EQUAL(strings::to_string_dac(0.9, 6), "0.9", ());
+  TEST_EQUAL(strings::to_string_dac(-1.0, 30), "-1", ());
+  TEST_EQUAL(strings::to_string_dac(-0.99, 30), "-0.99", ());
+
+  TEST_EQUAL(strings::to_string_dac(1.0E30, 6), "1e+30", ());
+  TEST_EQUAL(strings::to_string_dac(1.0E-15, 15), "0.000000000000001", ());
+  TEST_EQUAL(strings::to_string_dac(1.0 + 1.0E-14, 15), "1.00000000000001", ());
 }
 
 struct FunctorTester
diff --git a/base/string_utils.cpp b/base/string_utils.cpp
index 6a5c42bb9a..2de39807af 100644
--- a/base/string_utils.cpp
+++ b/base/string_utils.cpp
@@ -118,9 +118,12 @@ namespace
 {
   char ascii_to_lower(char in)
   {
-    static char const diff = 'Z'-'z';
-    if (in <= 'Z' && in >= 'A')
-      return (in-diff);
+    char const diff = 'z' - 'Z';
+    STATIC_ASSERT(diff == 'a' - 'A');
+    STATIC_ASSERT(diff > 0);
+
+    if (in >= 'A' && in <= 'Z')
+      return (in + diff);
     return in;
   }
 }
@@ -169,7 +172,10 @@ bool StartsWith(string const & s1, char const * s2)
 
 string to_string_dac(double d, int dac)
 {
+  dac = min(numeric_limits<double>::digits10, dac);
+
   ostringstream ss;
+
   if (d < 1. && d > -1.)
   {
     string res;
@@ -188,17 +194,15 @@ string to_string_dac(double d, int dac)
     return res;
   }
 
-  double fD = fabs(d);
-
   // Calc digits before comma (log10).
-  int dbc = 0;
-  while (fD >= 1.0 && dbc < numeric_limits<double>::digits10)
+  double fD = fabs(d);
+  while (fD >= 1.0 && dac < numeric_limits<double>::digits10)
   {
     fD /= 10.0;
-    ++dbc;
+    ++dac;
   }
 
-  ss << setprecision(dac + dbc) << d;
+  ss << setprecision(dac) << d;
   return ss.str();
 }