diff --git a/src/main/java/org/apache/maven/plugins/toolchain/jdk/ToolchainDiscoverer.java b/src/main/java/org/apache/maven/plugins/toolchain/jdk/ToolchainDiscoverer.java
index 897e69e..19199a5 100644
--- a/src/main/java/org/apache/maven/plugins/toolchain/jdk/ToolchainDiscoverer.java
+++ b/src/main/java/org/apache/maven/plugins/toolchain/jdk/ToolchainDiscoverer.java
@@ -238,8 +238,10 @@ ToolchainModel getToolchainModel(Path jdk) {
         ToolchainModel model = cache.get(jdk);
         if (model == null) {
             model = doGetToolchainModel(jdk);
-            cache.put(jdk, model);
-            cacheModified = true;
+            if (model != null) {
+                cache.put(jdk, model);
+                cacheModified = true;
+            }
         }
         return model;
     }