diff --git a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java
index ac2cddfefa9..538a5c494a6 100644
--- a/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java
+++ b/modules/swagger-codegen/src/main/java/io/swagger/codegen/languages/PhpClientCodegen.java
@@ -330,6 +330,9 @@ public class PhpClientCodegen extends DefaultCodegen implements CodegenConfig {
 
     @Override
     public String toModelName(String name) {
+        // Note: backslash ("\\") is allowed for e.g. "\\DateTime"
+        name = name.replaceAll("[^\\w\\\\]+", "_");
+
         // model name cannot use reserved keyword
         if (reservedWords.contains(name)) {
             escapeReservedWord(name); // e.g. return => _return