diff --git a/action.yml b/action.yml
index bf8e895a..5e0e2f37 100644
--- a/action.yml
+++ b/action.yml
@@ -17,11 +17,9 @@ inputs:
     required: false
   cmake:
     description: "The cmake version to install."
-    default: "3.20.2"
     required: false
   ninja:
     description: "The ninja version to install."
-    default: "1.10.2"
     required: false
   conan:
     description: "The conan version to install."
diff --git a/src/cmake/cmake.ts b/src/cmake/cmake.ts
index 9ae31115..7c4c2d13 100644
--- a/src/cmake/cmake.ts
+++ b/src/cmake/cmake.ts
@@ -58,7 +58,9 @@ function getCmakePackageInfo(version: string, platform?: NodeJS.Platform): Packa
   }
 }
 
+const default_cmake_version = "3.20.2"
+
 /** Setup cmake */
 export function setupCmake(version: string, setupCppDir: string): Promise<InstallationInfo> {
-  return setupBin("cmake", version, getCmakePackageInfo, setupCppDir)
+  return setupBin("cmake", version === "true" ? default_cmake_version : version, getCmakePackageInfo, setupCppDir)
 }
diff --git a/src/main.ts b/src/main.ts
index c84d8359..83a510fe 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -20,7 +20,7 @@ function maybeGetInput(key: string) {
   if (value !== "false" && value !== "") {
     return value
   }
-  return undefined
+  return undefined // skip installation
 }
 
 export async function main(): Promise<number> {
diff --git a/src/ninja/ninja.ts b/src/ninja/ninja.ts
index dddad01d..ae11f103 100644
--- a/src/ninja/ninja.ts
+++ b/src/ninja/ninja.ts
@@ -26,6 +26,8 @@ function getNinjaPackageInfo(version: string, platform: NodeJS.Platform): Packag
   }
 }
 
+const default_ninja_version = "1.10.2"
+
 export function setupNinja(version: string, setupCppDir: string): Promise<InstallationInfo> {
-  return setupBin("ninja", version, getNinjaPackageInfo, setupCppDir)
+  return setupBin("ninja", version === "true" ? default_ninja_version : version, getNinjaPackageInfo, setupCppDir)
 }