diff --git a/lib/spack/spack/build_environment.py b/lib/spack/spack/build_environment.py
index 86bfa5d52a..65ad1dcbb4 100644
--- a/lib/spack/spack/build_environment.py
+++ b/lib/spack/spack/build_environment.py
@@ -480,9 +480,12 @@ def set_wrapper_variables(pkg, env):
     env.set(SPACK_DEBUG_LOG_ID, pkg.spec.format("{name}-{hash:7}"))
     env.set(SPACK_DEBUG_LOG_DIR, spack.main.spack_working_dir)
 
-    # Find ccache binary and hand it to build environment
     if spack.config.get("config:ccache"):
+        # Enable ccache in the compiler wrapper
         env.set(SPACK_CCACHE_BINARY, spack.util.executable.which_string("ccache", required=True))
+    else:
+        # Avoid cache pollution if a build system forces `ccache <compiler wrapper invocation>`.
+        env.set("CCACHE_DISABLE", "1")
 
     # Gather information about various types of dependencies
     link_deps = set(pkg.spec.traverse(root=False, deptype=("link")))