diff --git a/sandbox.go b/sandbox.go
index 36d2f28..f63c360 100644
--- a/sandbox.go
+++ b/sandbox.go
@@ -41,6 +41,9 @@
 	progName = "prog.go"
 )
 
+// Runtime error strings that will not be cached if found in an Event message.
+var nonCachingRuntimeErrors = []string{"out of memory", "cannot allocate memory"}
+
 type request struct {
 	Body string
 }
@@ -87,6 +90,18 @@
 				http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
 				return
 			}
+			for _, el := range resp.Events {
+				if el.Kind != "stderr" {
+					continue
+				}
+				for _, e := range nonCachingRuntimeErrors {
+					if strings.Contains(el.Message, e) {
+						s.log.Errorf("cmdFunc runtime error: %q", el.Message)
+						http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
+						return
+					}
+				}
+			}
 			if err := s.cache.Set(key, resp); err != nil {
 				s.log.Errorf("cache.Set(%q, resp): %v", key, err)
 			}
diff --git a/server_test.go b/server_test.go
index 8621742..6314193 100644
--- a/server_test.go
+++ b/server_test.go
@@ -166,6 +166,15 @@
 		if r.Body == "error" {
 			return &response{Errors: "errors"}, nil
 		}
+		if r.Body == "oom-error" {
+			// To throw an oom in a local playground instance, increase the server timeout
+			// to 20 seconds (within sandbox.go), spin up the Docker instance and run
+			// this code: https://play.golang.org/p/aaCv86m0P14.
+			return &response{Events: []Event{{"out of memory", "stderr", 0}}}, nil
+		}
+		if r.Body == "allocate-memory-error" {
+			return &response{Events: []Event{{"cannot allocate memory", "stderr", 0}}}, nil
+		}
 		resp := &response{Events: []Event{{r.Body, "stdout", 0}}}
 		return resp, nil
 	})
@@ -191,6 +200,10 @@
 			[]byte(`{"Errors":"errors","Events":null}
 `),
 		},
+		{"Out of memory error in response body event message", http.MethodPost, http.StatusInternalServerError,
+			[]byte(`{"Body":"oom-error"}`), nil},
+		{"Cannot allocate memory error in response body event message", http.MethodPost, http.StatusInternalServerError,
+			[]byte(`{"Body":"allocate-memory-error"}`), nil},
 	}
 
 	for _, tc := range testCases {