diff --git a/README.md b/README.md
index 05e87cc..5dddf16 100644
--- a/README.md
+++ b/README.md
@@ -313,7 +313,7 @@ The element must be a number inside the specified `integer` and `fraction` range
 
 - Applies to : `String`, `Byte`, `Short`, `Int`, `Long`, `BigDecimal`, `BigInteger`, `Float`, `Lists`
 
-- SDL : `directive @Digits(integer : Int!, fraction : Int!, message : String = "graphql.validation.Digits.message") on ARGUMENT_DEFINITION | INPUT_FIELD_DEFINITION`
+- SDL : `directive @Digits(integer : Int!, fraction : Int, message : String = "graphql.validation.Digits.message") on ARGUMENT_DEFINITION | INPUT_FIELD_DEFINITION`
 
 - Message : `graphql.validation.Digits.message`
 
diff --git a/src/main/java/graphql/validation/constraints/AbstractDirectiveConstraint.java b/src/main/java/graphql/validation/constraints/AbstractDirectiveConstraint.java
index ddb7a7f..3cfd0e9 100644
--- a/src/main/java/graphql/validation/constraints/AbstractDirectiveConstraint.java
+++ b/src/main/java/graphql/validation/constraints/AbstractDirectiveConstraint.java
@@ -27,6 +27,7 @@
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
 import static graphql.schema.GraphQLTypeUtil.isList;
 import static graphql.validation.rules.ValidationEnvironment.ValidatedElement.FIELD;
@@ -198,23 +199,28 @@ protected boolean isOneOfTheseTypes(GraphQLInputType inputType, Collection<Graph
     }
 
     /**
-     * Returns an integer argument from a directive (or its default) and throws an assertion of the argument is null
+     * Returns an integer argument from a directive (or its default) and throws an assertion if the argument is null
      *
      * @param directive the directive to check
      * @param argName   the argument name
      * @return a non null value
      */
     protected int getIntArg(GraphQLAppliedDirective directive, String argName) {
-        GraphQLAppliedDirectiveArgument argument = directive.getArgument(argName);
-        if (argument == null) {
-            return assertExpectedArgType(argName, "Int");
-        }
+        return getIntArgOpt(directive, argName)
+            .orElseGet(() -> assertExpectedArgType(argName, "Int"));
+    }
 
-        Number value = argument.getValue();
-        if (value == null) {
-            return assertExpectedArgType(argName, "Int");
-        }
-        return value.intValue();
+    /**
+     * Returns an optional integer argument from a directive (or its default), or empty Optional if the argument is null.
+     *
+     * @param directive the directive to check
+     * @param argName   the argument name
+     * @return an optional null value
+     */
+    protected Optional<Integer> getIntArgOpt(GraphQLAppliedDirective directive, String argName) {
+        return Optional.ofNullable(directive.getArgument(argName))
+            .map(GraphQLAppliedDirectiveArgument::<Number>getValue)
+            .map(Number::intValue);
     }
 
     /**
diff --git a/src/main/java/graphql/validation/constraints/standard/DigitsConstraint.java b/src/main/java/graphql/validation/constraints/standard/DigitsConstraint.java
index fe94bbd..a8f963e 100644
--- a/src/main/java/graphql/validation/constraints/standard/DigitsConstraint.java
+++ b/src/main/java/graphql/validation/constraints/standard/DigitsConstraint.java
@@ -10,6 +10,7 @@
 import java.math.BigDecimal;
 import java.util.Collections;
 import java.util.List;
+import java.util.Optional;
 
 import static graphql.validation.constraints.GraphQLScalars.GRAPHQL_NUMBER_AND_STRING_TYPES;
 
@@ -21,14 +22,14 @@ public DigitsConstraint() {
     @Override
     public Documentation getDocumentation() {
         return Documentation.newDocumentation()
-                .messageTemplate(getMessageTemplate())
-                .description("The element must be a number inside the specified `integer` and `fraction` range.")
-                .example("buyCar( carCost : Float @Digits(integer : 5, fraction : 2) : DriverDetails")
-                .applicableTypes(GRAPHQL_NUMBER_AND_STRING_TYPES)
-                .directiveSDL("directive @Digits(integer : Int!, fraction : Int!, message : String = \"%s\") " +
-                                "on ARGUMENT_DEFINITION | INPUT_FIELD_DEFINITION",
-                        getMessageTemplate())
-                .build();
+            .messageTemplate(getMessageTemplate())
+            .description("The element must be a number inside the specified `integer` and optionally inside `fraction` range.")
+            .example("buyCar( carCost : Float @Digits(integer : 5, fraction : 2) : DriverDetails")
+            .applicableTypes(GRAPHQL_NUMBER_AND_STRING_TYPES)
+            .directiveSDL("directive @Digits(integer : Int!, fraction : Int, message : String = \"%s\") " +
+                    "on ARGUMENT_DEFINITION | INPUT_FIELD_DEFINITION",
+                getMessageTemplate())
+            .build();
     }
 
     @Override
@@ -43,28 +44,40 @@ protected List<GraphQLError> runConstraint(ValidationEnvironment validationEnvir
 
         GraphQLAppliedDirective directive = validationEnvironment.getContextObject(GraphQLAppliedDirective.class);
         int maxIntegerLength = getIntArg(directive, "integer");
-        int maxFractionLength = getIntArg(directive, "fraction");
+        Optional<Integer> maxFractionLengthOpt = getIntArgOpt(directive, "fraction");
 
         boolean isOk;
         try {
             BigDecimal bigNum = asBigDecimal(validatedValue);
-            isOk = isOk(bigNum, maxIntegerLength, maxFractionLength);
+            boolean isFractionPartOk = maxFractionLengthOpt
+                .map(maxFractionLength -> isFractionPartOk(bigNum, maxFractionLength))
+                .orElse(true);
+
+            isOk = isFractionPartOk && isIntegerPartOk(bigNum, maxIntegerLength);
         } catch (NumberFormatException e) {
             isOk = false;
         }
 
         if (!isOk) {
-            return mkError(validationEnvironment, "integer", maxIntegerLength, "fraction", maxFractionLength);
+            return mkError(
+                validationEnvironment,
+                "integer",
+                maxIntegerLength, "fraction",
+                maxFractionLengthOpt.map(Object::toString).orElse("unlimited")
+            );
         }
 
         return Collections.emptyList();
     }
 
-    private boolean isOk(BigDecimal bigNum, int maxIntegerLength, int maxFractionLength) {
-        int integerPartLength = bigNum.precision() - bigNum.scale();
-        int fractionPartLength = Math.max(bigNum.scale(), 0);
+    private static boolean isIntegerPartOk(BigDecimal bigNum, int maxIntegerLength) {
+        final int integerPartLength = bigNum.precision() - bigNum.scale();
+        return maxIntegerLength >= integerPartLength;
+    }
 
-        return maxIntegerLength >= integerPartLength && maxFractionLength >= fractionPartLength;
+    private static boolean isFractionPartOk(BigDecimal bigNum, int maxFractionLength) {
+        final int fractionPartLength = Math.max(bigNum.scale(), 0);
+        return maxFractionLength >= fractionPartLength;
     }
 
     @Override
diff --git a/src/test/groovy/graphql/validation/constraints/standard/DigitsConstraintTest.groovy b/src/test/groovy/graphql/validation/constraints/standard/DigitsConstraintTest.groovy
index 772ec36..701746c 100644
--- a/src/test/groovy/graphql/validation/constraints/standard/DigitsConstraintTest.groovy
+++ b/src/test/groovy/graphql/validation/constraints/standard/DigitsConstraintTest.groovy
@@ -23,6 +23,7 @@ class DigitsConstraintTest extends BaseConstraintTestSupport {
         'field( arg : String @Digits(integer : 5, fraction : 2) ) : ID'     | null                           | ''
         'field( arg : String @Digits(integer : 5, fraction : 2) ) : ID'     | Byte.valueOf("0")              | ''
         'field( arg : String @Digits(integer : 5, fraction : 2) ) : ID'     | Double.valueOf("500.2")        | ''
+        'field( arg : String @Digits(integer : 5) ) : ID'                   | Double.valueOf("500.2345678")  | ''
 
         'field( arg : String @Digits(integer : 5, fraction : 2) ) : ID'     | new BigDecimal("-12345.12")    | ''
         'field( arg : String @Digits(integer : 5, fraction : 2) ) : ID'     | new BigDecimal("-123456.12")   | 'Digits;path=/arg;val:-123456.12;\t'