diff --git a/src/main/java/com/ethlo/time/DateTime.java b/src/main/java/com/ethlo/time/DateTime.java
index 3be8072..c62c03c 100644
--- a/src/main/java/com/ethlo/time/DateTime.java
+++ b/src/main/java/com/ethlo/time/DateTime.java
@@ -375,7 +375,7 @@ private String toString(final DateTime date, final Field lastIncluded, final int
     {
         if (lastIncluded.ordinal() > date.getMostGranularField().ordinal())
         {
-            throw new DateTimeFormatException("Requested granularity was " + lastIncluded.name() + ", but contains only granularity " + date.getMostGranularField().name());
+            throw new DateTimeFormatException(String.format("Requested granularity was %s, but contains only granularity %s", lastIncluded.name(), date.getMostGranularField().name()));
         }
         final TimezoneOffset tz = date.getOffset().orElse(null);
         final char[] buffer = new char[35];
@@ -580,7 +580,7 @@ private void validated()
 
         if (second > 59)
         {
-            throw new DateTimeException("Invalid value for SecondOfMinute (valid values 0 - 59): " + second);
+            throw new DateTimeException(String.format("Invalid value for SecondOfMinute (valid values 0 - 59): %d", second));
         }
     }
 
diff --git a/src/main/java/com/ethlo/time/internal/ErrorUtil.java b/src/main/java/com/ethlo/time/internal/ErrorUtil.java
index 806218f..036138b 100644
--- a/src/main/java/com/ethlo/time/internal/ErrorUtil.java
+++ b/src/main/java/com/ethlo/time/internal/ErrorUtil.java
@@ -34,17 +34,17 @@ private ErrorUtil()
 
     public static DateTimeParseException raiseUnexpectedCharacter(String chars, int index)
     {
-        throw new DateTimeParseException("Unexpected character " + chars.charAt(index) + " at position " + (index + 1) + ": " + chars, chars, index);
+        throw new DateTimeParseException(String.format("Unexpected character %s at position %d: %s", chars.charAt(index), index + 1, chars), chars, index);
     }
 
     public static DateTimeParseException raiseUnexpectedEndOfText(final String chars, final int offset)
     {
-        throw new DateTimeParseException("Unexpected end of input: " + chars, chars, offset);
+        throw new DateTimeParseException(String.format("Unexpected end of input: %s", chars), chars, offset);
     }
 
     public static DateTimeParseException raiseMissingGranularity(Field field, final String chars, final int offset)
     {
-        throw new DateTimeParseException("Unexpected end of input, missing field " + field.name() + ": " + chars, chars, offset);
+        throw new DateTimeParseException(String.format("Unexpected end of input, missing field %s: %s", field.name(), chars), chars, offset);
     }
 
     public static void assertPositionContains(Field field, String chars, int index, char expected)
@@ -56,7 +56,7 @@ public static void assertPositionContains(Field field, String chars, int index,
 
         if (chars.charAt(index) != expected)
         {
-            throw new DateTimeParseException("Expected character " + expected + " at position " + (index + 1) + ", found " + chars.charAt(index) + ": " + chars, chars, index);
+            throw new DateTimeParseException(String.format("Expected character %s at position %d, found %s: %s", expected, index + 1, chars.charAt(index), chars), chars, index);
         }
     }
 
@@ -64,12 +64,12 @@ public static void assertFractionDigits(String chars, int fractionDigits, int id
     {
         if (fractionDigits == 0)
         {
-            throw new DateTimeParseException("Must have at least 1 fraction digit: " + chars, chars, idx);
+            throw new DateTimeParseException(String.format("Must have at least 1 fraction digit: %s", chars), chars, idx);
         }
 
         if (fractionDigits > MAX_FRACTION_DIGITS)
         {
-            throw new DateTimeParseException("Maximum supported number of fraction digits in second is 9, got " + fractionDigits + ": " + chars, chars, idx);
+            throw new DateTimeParseException(String.format("Maximum supported number of fraction digits in second is 9, got %d: %s", fractionDigits, chars), chars, idx);
         }
     }
 }
diff --git a/src/main/java/com/ethlo/time/internal/ITUParser.java b/src/main/java/com/ethlo/time/internal/ITUParser.java
index 719cda7..d2bceb1 100644
--- a/src/main/java/com/ethlo/time/internal/ITUParser.java
+++ b/src/main/java/com/ethlo/time/internal/ITUParser.java
@@ -84,7 +84,8 @@ private static void assertAllowedDateTimeSeparator(final int offset, final Strin
         final char needle = chars.charAt(index);
         if (!config.isDateTimeSeparator(needle))
         {
-            throw new DateTimeParseException("Expected character " + (config.getDateTimeSeparators().length > 1 ? Arrays.toString(config.getDateTimeSeparators()) : config.getDateTimeSeparators()[0]) + " at position " + (index + 1) + ", found " + chars.charAt(index) + ": " + chars, chars, index);
+            final String allowedCharStr = config.getDateTimeSeparators().length > 1 ? Arrays.toString(config.getDateTimeSeparators()) : Character.toString(config.getDateTimeSeparators()[0]);
+            throw new DateTimeParseException(String.format("Expected character %s at position %d, found %s: %s", allowedCharStr, index + 1, chars.charAt(index), chars), chars, index);
         }
     }
 
@@ -111,7 +112,7 @@ private static TimezoneOffset parseTimezone(int offset, final ParseConfig parseC
 
         if (left < 6)
         {
-            throw new DateTimeParseException("Invalid timezone offset: " + chars, chars, idx);
+            throw new DateTimeParseException(String.format("Invalid timezone offset: %s", chars), chars, idx);
         }
 
         int hours = parsePositiveInt(chars, idx + 1, idx + 3);
@@ -137,7 +138,7 @@ private static void assertNoMoreChars(final int offset, final ParseConfig parseC
         {
             if (chars.length() > lastUsed + 1)
             {
-                throw new DateTimeParseException("Trailing junk data after position " + (lastUsed + 2) + ": " + chars, chars, lastUsed + 1);
+                throw new DateTimeParseException(String.format("Trailing junk data after position %d: %s", lastUsed + 2, chars), chars, lastUsed + 1);
             }
         }
     }
@@ -153,12 +154,12 @@ public static DateTime parseLenient(final String chars, final ParseConfig parseC
 
         if (availableLength < 0)
         {
-            throw new IndexOutOfBoundsException("offset is " + offset + " which is equal to or larger than the input length of " + chars.length());
+            throw new IndexOutOfBoundsException(String.format("offset is %d which is equal to or larger than the input length of %d", offset, chars.length()));
         }
 
         if (offset < 0)
         {
-            throw new IndexOutOfBoundsException("offset cannot be negative, was " + offset);
+            throw new IndexOutOfBoundsException(String.format("offset cannot be negative, was %d", offset));
         }
 
         // Date portion
@@ -289,6 +290,6 @@ public static OffsetDateTime parseDateTime(final String chars, int offset)
         }
         final Field field = dateTime.getMostGranularField();
         final Field nextGranularity = Field.values()[field.ordinal() + 1];
-        throw new DateTimeParseException("Unexpected end of input, missing field " + nextGranularity + ": " + chars, chars, field.getRequiredLength());
+        throw new DateTimeParseException(String.format("Unexpected end of input, missing field %s: %s", nextGranularity, chars), chars, field.getRequiredLength());
     }
 }
\ No newline at end of file