diff --git a/sys/alpha/alpha/trap.c b/sys/alpha/alpha/trap.c
index c0b13271412f..af9be44ea56c 100644
--- a/sys/alpha/alpha/trap.c
+++ b/sys/alpha/alpha/trap.c
@@ -298,11 +298,11 @@ trap(a0, a1, a2, entry, framep)
 		sticks = td->td_kse->ke_sticks;
 		td->td_frame = framep;
 #ifdef DIAGNOSTIC 			/* see the comment in ast() */
-		if (td->td_ucred)
-			panic("trap: thread got a cred while in userspace");
+		if (td->td_ucred != NULL)
+			panic("trap(): thread got a ucred while in userspace");
 		td->td_ucred = td->td_ucred_cache;
 		td->td_ucred_cache = NULL;
-#endif /* DIAGNOSTIC */
+#endif
 		if (td->td_ucred != p->p_ucred)
 			cred_update_thread(td);
 	} else {
diff --git a/sys/ia64/ia64/trap.c b/sys/ia64/ia64/trap.c
index 141ae9b666dc..bf5c2cd9987a 100644
--- a/sys/ia64/ia64/trap.c
+++ b/sys/ia64/ia64/trap.c
@@ -324,11 +324,11 @@ trap(int vector, int imm, struct trapframe *framep)
 		sticks = td->td_kse->ke_sticks;
 		td->td_frame = framep;
 #ifdef DIAGNOSTIC 			/* see the comment in ast() */
-		if (td->td_ucred)
-			panic("trap:thread got a cred while userspace");
+		if (td->td_ucred != NULL)
+			panic("trap(): thread got a ucred while in userspace");
 		td->td_ucred = td->td_ucred_cache;
 		td->td_ucred_cache = NULL;
-#endif /* DIAGNOSTIC */
+#endif
 		if (td->td_ucred != p->p_ucred)
 			cred_update_thread(td);
 	} else {
diff --git a/sys/powerpc/aim/trap.c b/sys/powerpc/aim/trap.c
index 5a08c63191f1..64cbf75ca7f9 100644
--- a/sys/powerpc/aim/trap.c
+++ b/sys/powerpc/aim/trap.c
@@ -227,11 +227,11 @@ trap(struct trapframe *frame)
 		sticks = td->td_kse->ke_sticks;
 		td->td_frame = frame;
 #ifdef DIAGNOSTIC 			/* see the comment in ast() */
-		if (td->td_ucred)
-			panic("trap:thread got a cred while userspace");
+		if (td->td_ucred != NULL)
+			panic("trap(): thread got a ucred while in userspace");
 		td->td_ucred = td->td_ucred_cache;
 		td->td_ucred_cache = NULL;
-#endif /* DIAGNOSTIC */
+#endif
 		if (td->td_ucred != p->p_ucred)
 			cred_update_thread(td);
 
diff --git a/sys/powerpc/powerpc/trap.c b/sys/powerpc/powerpc/trap.c
index 5a08c63191f1..64cbf75ca7f9 100644
--- a/sys/powerpc/powerpc/trap.c
+++ b/sys/powerpc/powerpc/trap.c
@@ -227,11 +227,11 @@ trap(struct trapframe *frame)
 		sticks = td->td_kse->ke_sticks;
 		td->td_frame = frame;
 #ifdef DIAGNOSTIC 			/* see the comment in ast() */
-		if (td->td_ucred)
-			panic("trap:thread got a cred while userspace");
+		if (td->td_ucred != NULL)
+			panic("trap(): thread got a ucred while in userspace");
 		td->td_ucred = td->td_ucred_cache;
 		td->td_ucred_cache = NULL;
-#endif /* DIAGNOSTIC */
+#endif
 		if (td->td_ucred != p->p_ucred)
 			cred_update_thread(td);
 
diff --git a/sys/sparc64/sparc64/trap.c b/sys/sparc64/sparc64/trap.c
index 13e74f8d973d..6302d45b4e1c 100644
--- a/sys/sparc64/sparc64/trap.c
+++ b/sys/sparc64/sparc64/trap.c
@@ -176,11 +176,11 @@ trap(struct trapframe *tf)
 		sticks = td->td_kse->ke_sticks;
 		td->td_frame = tf;
 #ifdef DIAGNOSTIC 			/* see the comment in ast() */
-		if (td->td_ucred)
-			panic("trap:thread got a cred while userspace");
+		if (td->td_ucred != NULL)
+			panic("trap(): thread got a ucred while in userspace");
 		td->td_ucred = td->td_ucred_cache;
 		td->td_ucred_cache = NULL;
-#endif /* DIAGNOSTIC */
+#endif
 		if (td->td_ucred != p->p_ucred)
 			cred_update_thread(td);
  	} else {