diff --git a/src/main/java/com/mojang/brigadier/ImmutableStringReader.java b/src/main/java/com/mojang/brigadier/ImmutableStringReader.java
index e605623..6e1c808 100644
--- a/src/main/java/com/mojang/brigadier/ImmutableStringReader.java
+++ b/src/main/java/com/mojang/brigadier/ImmutableStringReader.java
@@ -3,6 +3,8 @@
 
 package com.mojang.brigadier;
 
+import java.util.function.Predicate;
+
 public interface ImmutableStringReader {
     String getString();
 
@@ -25,4 +27,6 @@ public interface ImmutableStringReader {
     char peek(int offset);
 
     boolean isNext(char c);
+
+    boolean isNext(Predicate<Character> predicate);
 }
diff --git a/src/main/java/com/mojang/brigadier/StringReader.java b/src/main/java/com/mojang/brigadier/StringReader.java
index 4e1392e..13b4d9a 100644
--- a/src/main/java/com/mojang/brigadier/StringReader.java
+++ b/src/main/java/com/mojang/brigadier/StringReader.java
@@ -5,6 +5,8 @@ package com.mojang.brigadier;
 
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 
+import java.util.function.Predicate;
+
 public class StringReader implements ImmutableStringReader {
     private static final char SYNTAX_ESCAPE = '\\';
     private static final char SYNTAX_DOUBLE_QUOTE = '"';
@@ -81,6 +83,11 @@ public class StringReader implements ImmutableStringReader {
         return canRead() && peek() == c;
     }
 
+    @Override
+    public boolean isNext(Predicate<Character> predicate) {
+        return canRead() && predicate.test(peek());
+    }
+
     public char read() {
         return string.charAt(cursor++);
     }
@@ -98,14 +105,14 @@ public class StringReader implements ImmutableStringReader {
     }
 
     public void skipWhitespace() {
-        while (canRead() && Character.isWhitespace(peek())) {
+        while (isNext(Character::isWhitespace)) {
             skip();
         }
     }
 
     public int readInt() throws CommandSyntaxException {
         final int start = cursor;
-        while (canRead() && isAllowedNumber(peek())) {
+        while (isNext(StringReader::isAllowedNumber)) {
             skip();
         }
         final String number = string.substring(start, cursor);
@@ -122,7 +129,7 @@ public class StringReader implements ImmutableStringReader {
 
     public long readLong() throws CommandSyntaxException {
         final int start = cursor;
-        while (canRead() && isAllowedNumber(peek())) {
+        while (isNext(StringReader::isAllowedNumber)) {
             skip();
         }
         final String number = string.substring(start, cursor);
@@ -139,7 +146,7 @@ public class StringReader implements ImmutableStringReader {
 
     public double readDouble() throws CommandSyntaxException {
         final int start = cursor;
-        while (canRead() && isAllowedNumber(peek())) {
+        while (isNext(StringReader::isAllowedNumber)) {
             skip();
         }
         final String number = string.substring(start, cursor);
@@ -156,7 +163,7 @@ public class StringReader implements ImmutableStringReader {
 
     public float readFloat() throws CommandSyntaxException {
         final int start = cursor;
-        while (canRead() && isAllowedNumber(peek())) {
+        while (isNext(StringReader::isAllowedNumber)) {
             skip();
         }
         final String number = string.substring(start, cursor);
@@ -181,7 +188,7 @@ public class StringReader implements ImmutableStringReader {
 
     public String readUnquotedString() {
         final int start = cursor;
-        while (canRead() && isAllowedInUnquotedString(peek())) {
+        while (isNext(StringReader::isAllowedInUnquotedString)) {
             skip();
         }
         return string.substring(start, cursor);
diff --git a/src/test/java/com/mojang/brigadier/StringReaderTest.java b/src/test/java/com/mojang/brigadier/StringReaderTest.java
index bf08bb5..7ee7fce 100644
--- a/src/test/java/com/mojang/brigadier/StringReaderTest.java
+++ b/src/test/java/com/mojang/brigadier/StringReaderTest.java
@@ -6,6 +6,8 @@ package com.mojang.brigadier;
 import com.mojang.brigadier.exceptions.CommandSyntaxException;
 import org.junit.Test;
 
+import java.util.function.Predicate;
+
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
 import static org.junit.Assert.assertThat;
@@ -587,7 +589,7 @@ public class StringReaderTest {
     }
 
     @Test
-    public void isAt() {
+    public void isNext() {
         final StringReader reader = new StringReader("abc");
         assertThat(reader.isNext('a'), is(true));
         assertThat(reader.isNext('x'), is(false));
@@ -596,4 +598,15 @@ public class StringReaderTest {
         reader.skip();
         assertThat(reader.isNext('c'), is(false));
     }
+
+    @Test
+    public void isNext_predicate() {
+        final StringReader reader = new StringReader("abc");
+        final Predicate<Character> predicate = c -> (c == 'a' || c == 'b');
+        assertThat(reader.isNext(predicate), is(true));
+        reader.setCursor(1);
+        assertThat(reader.isNext(predicate), is(true));
+        reader.setCursor(2);
+        assertThat(reader.isNext(predicate), is(false));
+    }
 }
\ No newline at end of file