diff --git a/src/cppbor_parse.cpp b/src/cppbor_parse.cpp
index fcf0dac..ab01ee7 100644
--- a/src/cppbor_parse.cpp
+++ b/src/cppbor_parse.cpp
@@ -275,6 +275,9 @@
                     return handleBool(addlData, begin, pos, parseClient);
                 case NULL_V:
                     return handleNull(begin, pos, parseClient);
+                default:
+                    parseClient->error(begin, "Unsupported floating-point or simple value.");
+                    return {begin, nullptr};
             }
     }
     CHECK(false);  // Impossible to get here.