diff --git a/ffitest/so.c b/ffitest/so.c
index c1ddda76..2d1cc818 100644
--- a/ffitest/so.c
+++ b/ffitest/so.c
@@ -77,3 +77,11 @@ big struct_big(int i, double d) {
     ret.c = ret.a + ret.b + 1000;
     return ret;
 }
+
+void void_fn(void) {
+    printf("void fn ran\n");
+}
+
+void void_ret_fn(int x) {
+    printf("void fn ran: %d\n", x);
+}
diff --git a/ffitest/test.janet b/ffitest/test.janet
index e454fff7..bbfd6c09 100644
--- a/ffitest/test.janet
+++ b/ffitest/test.janet
@@ -62,10 +62,17 @@
   [i d]
   (native-call struct-big-fn-pointer struct-big-fn-sig i d))
 
+(def void-fn-pointer (native-lookup module "void_fn"))
+(def void-fn-sig (native-signature :default :void))
+(defn void-fn
+  []
+  (native-call void-fn-pointer void-fn-sig))
+
 #
 # Call functions
 #
 
+(pp (void-fn))
 (pp (int-fn 10 20))
 (pp (double-fn 1.5 2.5 3.5))
 (pp (double-many 1 2 3 4 5 6))
diff --git a/src/core/ffi.c b/src/core/ffi.c
index 36f03fa8..5a1b35cf 100644
--- a/src/core/ffi.c
+++ b/src/core/ffi.c
@@ -473,6 +473,7 @@ static JanetFFIWordSpec sysv64_classify(JanetFFIType type) {
             return clazz;
         }
         case JANET_FFI_TYPE_VOID:
+            return JANET_SYSV64_NO_CLASS;
         default:
             janet_panic("nyi");
             return JANET_SYSV64_NO_CLASS;
@@ -519,6 +520,9 @@ JANET_CORE_FN(cfun_ffi_signature,
                 mappings[i].type = decode_ffi_type(argv[i + 2]);
                 mappings[i].offset = 0;
                 mappings[i].spec = sysv64_classify(mappings[i].type);
+                if (mappings[i].spec == JANET_SYSV64_NO_CLASS) {
+                    janet_panic("unexpected void parameter");
+                }
                 size_t el_size = (type_size(mappings[i].type) + 7) / 8;
                 switch (mappings[i].spec) {
                     default: