diff --git a/design/mvp/Explainer.md b/design/mvp/Explainer.md
index ebf37a57..d8c0bdd1 100644
--- a/design/mvp/Explainer.md
+++ b/design/mvp/Explainer.md
@@ -2539,17 +2539,18 @@ plainname         ::= <label>
                     | '[method]' <label> '.' <label>
                     | '[static]' <label> '.' <label>
 label             ::= <first-fragment> ( '-' <fragment> )*
-first-fragment    ::= [a-z] <word>
-                    | [A-Z] <acronym>
+first-fragment    ::= <first-word>
+                    | <first-acronym>
+first-word        ::= [a-z] [0-9a-z]*
+first-acronym     ::= [A-Z] [0-9A-Z]*
 fragment          ::= <word>
                     | <acronym>
-word              ::= [0-9a-z]*
-acronym           ::= [0-9A-Z]*
+word              ::= [0-9a-z]+
+acronym           ::= [0-9A-Z]+
 interfacename     ::= <namespace> <label> <projection> <interfaceversion>?
                     | <namespace>+ <label> <projection>+ <interfaceversion>? 🪺
 namespace         ::= <words> ':'
-words             ::= <word>
-                    | <words> '-' <word>
+words             ::= <first-word> ( '-' <word> )*
 projection        ::= '/' <label>
 interfaceversion  ::= '@' <valid semver>
                     | '@' <canonversion> 🔗
diff --git a/test/names/kebab.wast b/test/names/kebab.wast
index 123e42cd..df135f87 100644
--- a/test/names/kebab.wast
+++ b/test/names/kebab.wast
@@ -8,6 +8,7 @@
   (import "B-1" (func))
   (import "B-1-C-2-D-3" (func))
   (import "a11-B11-123-ABC-abc" (func))
+  (import "ns-1-a:b-1-c/D-2" (func))
 ))
 (assert_invalid
   (component
@@ -17,3 +18,43 @@
   (component
     (import "1-a" (func)))
   "is not in kebab case")
+(assert_invalid
+  (component
+    (import "" (func)))
+  "is not in kebab case")
+(assert_invalid
+  (component
+    (import "a-" (func)))
+  "is not in kebab case")
+(assert_invalid
+  (component
+    (import "a--" (func)))
+  "is not in kebab case")
+(assert_invalid
+  (component
+    (import "1:a/b" (func)))
+  "is not in kebab case")
+(assert_invalid
+  (component
+    (import "A:b/c" (func)))
+  "is not a valid extern name")
+(assert_invalid
+  (component
+    (import "1:b/c" (func)))
+  "is not a valid extern name")
+(assert_invalid
+  (component
+    (import "ns-A:b/c" (func)))
+  "is not a valid extern name")
+(assert_invalid
+  (component
+    (import "ns:A/b" (func)))
+  "is not a valid extern name")
+(assert_invalid
+  (component
+    (import "ns:1/a" (func)))
+  "is not a valid extern name")
+(assert_invalid
+  (component
+    (import "ns:pkg-A/b" (func)))
+  "is not a valid extern name")