diff --git a/modules/openapi-generator/src/main/java/org/openapitools/codegen/templating/mustache/CamelCaseLambda.java b/modules/openapi-generator/src/main/java/org/openapitools/codegen/templating/mustache/CamelCaseLambda.java
index cf2f2571dc38..034d0cee76d7 100644
--- a/modules/openapi-generator/src/main/java/org/openapitools/codegen/templating/mustache/CamelCaseLambda.java
+++ b/modules/openapi-generator/src/main/java/org/openapitools/codegen/templating/mustache/CamelCaseLambda.java
@@ -62,7 +62,7 @@ public CamelCaseLambda escapeAsParamName(final Boolean escape) {
 
     @Override
     public void execute(Template.Fragment fragment, Writer writer) throws IOException {
-        String text = camelize(fragment.execute(), lowercaseFirstLetter);
+        String text = camelize(fragment.execute().replace(" ", "_"), lowercaseFirstLetter);
         if (generator != null) {
             text = generator.sanitizeName(text);
             if (generator.reservedWords().contains(text)) {
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/templating/mustache/CamelCaseLambdaTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/templating/mustache/CamelCaseLambdaTest.java
index f984adcb0f80..101b80adb120 100644
--- a/modules/openapi-generator/src/test/java/org/openapitools/codegen/templating/mustache/CamelCaseLambdaTest.java
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/templating/mustache/CamelCaseLambdaTest.java
@@ -33,6 +33,15 @@ public void camelCaseTest() {
         test("inputText", "{{#camelcase}}Input-text{{/camelcase}}", ctx);
     }
 
+    @Test
+    public void camelCaseSpaceTest() {
+        // Given
+        Map<String, Object> ctx = context("camelcase", new CamelCaseLambda());
+
+        // When & Then
+        test("inputTextApi", "{{#camelcase}}Input text  api{{/camelcase}}", ctx);
+    }
+
     @Test
     public void camelCaseReservedWordTest() {
         // Given
diff --git a/modules/openapi-generator/src/test/java/org/openapitools/codegen/templating/mustache/PascalCaseLambdaTest.java b/modules/openapi-generator/src/test/java/org/openapitools/codegen/templating/mustache/PascalCaseLambdaTest.java
new file mode 100644
index 000000000000..30a3d0ef4ebd
--- /dev/null
+++ b/modules/openapi-generator/src/test/java/org/openapitools/codegen/templating/mustache/PascalCaseLambdaTest.java
@@ -0,0 +1,75 @@
+package org.openapitools.codegen.templating.mustache;
+
+import static org.mockito.AdditionalAnswers.returnsFirstArg;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.when;
+
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.Map;
+
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.openapitools.codegen.CodegenConfig;
+import org.testng.annotations.BeforeMethod;
+import org.testng.annotations.Test;
+
+public class PascalCaseLambdaTest extends LambdaTest {
+
+    @Mock
+    CodegenConfig generator;
+
+    @BeforeMethod
+    public void setup() {
+        MockitoAnnotations.initMocks(this);
+    }
+
+    @Test
+    public void pascalCaseTest() {
+        // Given
+        Map<String, Object> ctx = context("pascalcase", new CamelCaseLambda(false));
+
+        // When & Then
+        test("InputText", "{{#pascalcase}}Input-text{{/pascalcase}}", ctx);
+        test("InputText", "{{#pascalcase}}Input_text{{/pascalcase}}", ctx);
+        test("", "{{#pascalcase}}{{/pascalcase}}", ctx);
+
+    }
+
+    @Test
+    public void pascalCaseSpaceTest() {
+        // Given
+        Map<String, Object> ctx = context("pascalcase", new CamelCaseLambda(false));
+
+        // When & Then
+        test("InputTextApi", "{{#pascalcase}}Input text  api{{/pascalcase}}", ctx);
+    }
+
+    @Test
+    public void pascalCaseReservedWordTest() {
+        // Given
+        Map<String, Object> ctx = context("pascalcase", new CamelCaseLambda(false).generator(generator));
+
+        when(generator.sanitizeName(anyString())).then(returnsFirstArg());
+        when(generator.reservedWords()).thenReturn(new HashSet<String>(Arrays.asList("ReservedWord")));
+        when(generator.escapeReservedWord("ReservedWord")).thenReturn("escapedReservedWord");
+
+        // When & Then
+        test("escapedReservedWord", "{{#pascalcase}}reserved-word{{/pascalcase}}", ctx);
+    }
+
+    @Test
+    public void pascalCaseEscapeParamTest() {
+        // Given
+        Map<String, Object> ctx = context("pascalcase", new CamelCaseLambda(false)
+                .generator(generator).escapeAsParamName(true));
+
+        when(generator.sanitizeName(anyString())).then(returnsFirstArg());
+        when(generator.reservedWords()).thenReturn(new HashSet<String>());
+        when(generator.toParamName("InputText")).thenReturn("inputTextAsParam");
+
+        // When & Then
+        test("inputTextAsParam", "{{#pascalcase}}Input_text{{/pascalcase}}", ctx);
+    }
+
+}