diff --git a/doc/environments/groupthm/groupthm.dtx b/doc/environments/groupthm/groupthm.dtx
index 48ebea5..22ae60f 100644
--- a/doc/environments/groupthm/groupthm.dtx
+++ b/doc/environments/groupthm/groupthm.dtx
@@ -1284,7 +1284,7 @@
     \cs_if_exist:cTF { @@_use_group_#1: }
       {
         \msg_error:nnnnn { groupthm } { wrong ~ definition }
-          { group } { #1 } { already }
+          { theorem ~ group } { #1 } { already }
       }
       {
         \@@_declare_theorem_group_aux:nnnnn { #1 } { #2 } { #3 } { #4 } { #5 }
@@ -1313,7 +1313,7 @@
       }
       {
         \msg_error:nnnnn { groupthm } { wrong ~ definition }
-          { group } { #1 } { not }
+          { theorem ~ group } { #1 } { not }
       }
   }
 %    \end{macrocode}
diff --git a/doc/environments/groupthm/groupthm.sty b/doc/environments/groupthm/groupthm.sty
index c768656..b4c1f55 100644
--- a/doc/environments/groupthm/groupthm.sty
+++ b/doc/environments/groupthm/groupthm.sty
@@ -48,7 +48,7 @@
 }
 \msg_new:nnn { groupthm } { wrong ~ definition }
 {
-  Bad ~ definition ~ of ~ #1 ~ '#2' ~ \msg_line_context:, ~ #1 ~ is ~ #3 defined.
+  Bad ~ definition ~ of ~ #1 ~ '#2' ~ \msg_line_context:, ~ #1 ~ is ~ #3 ~ defined.
 }
 \hook_new:n { __groupthm/prename   }
 \hook_new:n { __groupthm/postname  }