diff --git a/src/common/scripting/interface/stringformat.cpp b/src/common/scripting/interface/stringformat.cpp
index b5b88a695..9e6433f53 100644
--- a/src/common/scripting/interface/stringformat.cpp
+++ b/src/common/scripting/interface/stringformat.cpp
@@ -526,6 +526,27 @@ DEFINE_ACTION_FUNCTION_NATIVE(FStringStruct, CharLower, StringCharLower)
 	ACTION_RETURN_INT(StringCharLower(ch));
 }
 
+static int StringIsInt(FString *self)
+{
+	return self->IsInt();
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(FStringStruct, IsInt, StringIsInt)
+{
+	PARAM_SELF_STRUCT_PROLOGUE(FString);
+	ACTION_RETURN_INT(self->IsInt());
+}
+
+static int StringIsDouble(FString *self)
+{
+	return self->IsFloat();
+}
+
+DEFINE_ACTION_FUNCTION_NATIVE(FStringStruct, IsDouble, StringIsDouble)
+{
+	PARAM_SELF_STRUCT_PROLOGUE(FString);
+	ACTION_RETURN_INT(self->IsFloat());
+}
 
 static int StringToInt(FString *self, int base)
 {
diff --git a/wadsrc/static/zscript/engine/base.zs b/wadsrc/static/zscript/engine/base.zs
index 5abd62422..b7e95b1ba 100644
--- a/wadsrc/static/zscript/engine/base.zs
+++ b/wadsrc/static/zscript/engine/base.zs
@@ -975,8 +975,12 @@ struct StringStruct native unsafe(internal)
 	native String MakeLower() const;
 	native static int CharUpper(int ch);
 	native static int CharLower(int ch);
+
+	native bool IsInt() const;
+	native bool IsDouble() const;
 	native int ToInt(int base = 0) const;
 	native double ToDouble() const;
+
 	native void Split(out Array<String> tokens, String delimiter, EmptyTokenType keepEmpty = TOK_KEEPEMPTY) const;
 	native void AppendCharacter(int c);
 	native void DeleteLastCharacter();