Rename some check_wuffs_version status messages
diff --git a/cmd/wuffs-c/internal/cgen/cgen.go b/cmd/wuffs-c/internal/cgen/cgen.go
index add9970..70e8dc6 100644
--- a/cmd/wuffs-c/internal/cgen/cgen.go
+++ b/cmd/wuffs-c/internal/cgen/cgen.go
@@ -971,7 +971,7 @@
 	b.writes("if ((initialize_flags & WUFFS_INITIALIZE__ALREADY_ZEROED) == 0) {\n")
 	b.writes("memset(self, 0, sizeof_star_self);\n")
 	b.writes("} else if (self->private_impl.magic != 0) {\n")
-	b.writes("return wuffs_base__error__check_wuffs_version_not_applicable;\n")
+	b.writes("return wuffs_base__error__initialize_falsely_claimed_already_zeroed;\n")
 	b.writes("}\n")
 
 	// Call any ctors on sub-structs.
diff --git a/cmd/wuffs-c/internal/cgen/func.go b/cmd/wuffs-c/internal/cgen/func.go
index 04f12ad..865cab7 100644
--- a/cmd/wuffs-c/internal/cgen/func.go
+++ b/cmd/wuffs-c/internal/cgen/func.go
@@ -248,7 +248,7 @@
 		if g.currFunk.returnsStatus {
 			b.writes("(self->private_impl.magic == WUFFS_BASE__DISABLED) " +
 				"? wuffs_base__error__disabled_by_previous_error " +
-				": wuffs_base__error__check_wuffs_version_missing")
+				": wuffs_base__error__initialize_not_called")
 		} else if err := g.writeOutParamZeroValue(b, out); err != nil {
 			return err
 		}
diff --git a/lang/builtin/builtin.go b/lang/builtin/builtin.go
index d5a680c..492a92a 100644
--- a/lang/builtin/builtin.go
+++ b/lang/builtin/builtin.go
@@ -37,9 +37,9 @@
 	`"?bad workbuf length"`,
 	`"?bad wuffs version"`,
 	`"?cannot return a suspension"`,
-	`"?check_wuffs_version not applicable"`,
-	`"?check_wuffs_version missing"`,
 	`"?disabled by previous error"`,
+	`"?initialize falsely claimed already zeroed"`,
+	`"?initialize not called"`,
 	`"?interleaved coroutine calls"`,
 }
 
diff --git a/release/c/wuffs-unsupported-snapshot.c b/release/c/wuffs-unsupported-snapshot.c
index fbcf0b3..1dadf51 100644
--- a/release/c/wuffs-unsupported-snapshot.c
+++ b/release/c/wuffs-unsupported-snapshot.c
@@ -155,9 +155,9 @@
 extern const char* wuffs_base__error__bad_workbuf_length;
 extern const char* wuffs_base__error__bad_wuffs_version;
 extern const char* wuffs_base__error__cannot_return_a_suspension;
-extern const char* wuffs_base__error__check_wuffs_version_not_applicable;
-extern const char* wuffs_base__error__check_wuffs_version_missing;
 extern const char* wuffs_base__error__disabled_by_previous_error;
+extern const char* wuffs_base__error__initialize_falsely_claimed_already_zeroed;
+extern const char* wuffs_base__error__initialize_not_called;
 extern const char* wuffs_base__error__interleaved_coroutine_calls;
 
 static inline bool  //
@@ -4753,12 +4753,12 @@
 const char* wuffs_base__error__bad_wuffs_version = "?base: bad wuffs version";
 const char* wuffs_base__error__cannot_return_a_suspension =
     "?base: cannot return a suspension";
-const char* wuffs_base__error__check_wuffs_version_not_applicable =
-    "?base: check_wuffs_version not applicable";
-const char* wuffs_base__error__check_wuffs_version_missing =
-    "?base: check_wuffs_version missing";
 const char* wuffs_base__error__disabled_by_previous_error =
     "?base: disabled by previous error";
+const char* wuffs_base__error__initialize_falsely_claimed_already_zeroed =
+    "?base: initialize falsely claimed already zeroed";
+const char* wuffs_base__error__initialize_not_called =
+    "?base: initialize not called";
 const char* wuffs_base__error__interleaved_coroutine_calls =
     "?base: interleaved coroutine calls";
 
@@ -4951,7 +4951,7 @@
   if ((initialize_flags & WUFFS_INITIALIZE__ALREADY_ZEROED) == 0) {
     memset(self, 0, sizeof_star_self);
   } else if (self->private_impl.magic != 0) {
-    return wuffs_base__error__check_wuffs_version_not_applicable;
+    return wuffs_base__error__initialize_falsely_claimed_already_zeroed;
   }
   self->private_impl.magic = WUFFS_BASE__MAGIC;
   return NULL;
@@ -5950,7 +5950,7 @@
   if ((initialize_flags & WUFFS_INITIALIZE__ALREADY_ZEROED) == 0) {
     memset(self, 0, sizeof_star_self);
   } else if (self->private_impl.magic != 0) {
-    return wuffs_base__error__check_wuffs_version_not_applicable;
+    return wuffs_base__error__initialize_falsely_claimed_already_zeroed;
   }
   self->private_impl.magic = WUFFS_BASE__MAGIC;
   return NULL;
@@ -6228,7 +6228,7 @@
   if ((initialize_flags & WUFFS_INITIALIZE__ALREADY_ZEROED) == 0) {
     memset(self, 0, sizeof_star_self);
   } else if (self->private_impl.magic != 0) {
-    return wuffs_base__error__check_wuffs_version_not_applicable;
+    return wuffs_base__error__initialize_falsely_claimed_already_zeroed;
   }
   self->private_impl.magic = WUFFS_BASE__MAGIC;
   return NULL;
@@ -6276,7 +6276,7 @@
   if (self->private_impl.magic != WUFFS_BASE__MAGIC) {
     return (self->private_impl.magic == WUFFS_BASE__DISABLED)
                ? wuffs_base__error__disabled_by_previous_error
-               : wuffs_base__error__check_wuffs_version_missing;
+               : wuffs_base__error__initialize_not_called;
   }
   if ((self->private_impl.active_coroutine != 0) &&
       (self->private_impl.active_coroutine != 1)) {
@@ -8011,7 +8011,7 @@
   if ((initialize_flags & WUFFS_INITIALIZE__ALREADY_ZEROED) == 0) {
     memset(self, 0, sizeof_star_self);
   } else if (self->private_impl.magic != 0) {
-    return wuffs_base__error__check_wuffs_version_not_applicable;
+    return wuffs_base__error__initialize_falsely_claimed_already_zeroed;
   }
   self->private_impl.magic = WUFFS_BASE__MAGIC;
   return NULL;
@@ -8078,7 +8078,7 @@
   if (self->private_impl.magic != WUFFS_BASE__MAGIC) {
     return (self->private_impl.magic == WUFFS_BASE__DISABLED)
                ? wuffs_base__error__disabled_by_previous_error
-               : wuffs_base__error__check_wuffs_version_missing;
+               : wuffs_base__error__initialize_not_called;
   }
   if ((self->private_impl.active_coroutine != 0) &&
       (self->private_impl.active_coroutine != 1)) {
@@ -8587,7 +8587,7 @@
   if ((initialize_flags & WUFFS_INITIALIZE__ALREADY_ZEROED) == 0) {
     memset(self, 0, sizeof_star_self);
   } else if (self->private_impl.magic != 0) {
-    return wuffs_base__error__check_wuffs_version_not_applicable;
+    return wuffs_base__error__initialize_falsely_claimed_already_zeroed;
   }
   {
     wuffs_base__status z = wuffs_lzw__decoder__initialize(
@@ -8628,7 +8628,7 @@
   if (self->private_impl.magic != WUFFS_BASE__MAGIC) {
     return (self->private_impl.magic == WUFFS_BASE__DISABLED)
                ? wuffs_base__error__disabled_by_previous_error
-               : wuffs_base__error__check_wuffs_version_missing;
+               : wuffs_base__error__initialize_not_called;
   }
   if ((self->private_impl.active_coroutine != 0) &&
       (self->private_impl.active_coroutine != 1)) {
@@ -8791,7 +8791,7 @@
   if (self->private_impl.magic != WUFFS_BASE__MAGIC) {
     return (self->private_impl.magic == WUFFS_BASE__DISABLED)
                ? wuffs_base__error__disabled_by_previous_error
-               : wuffs_base__error__check_wuffs_version_missing;
+               : wuffs_base__error__initialize_not_called;
   }
 
   if (self->private_impl.f_call_sequence == 0) {
@@ -8818,7 +8818,7 @@
   if (self->private_impl.magic != WUFFS_BASE__MAGIC) {
     return (self->private_impl.magic == WUFFS_BASE__DISABLED)
                ? wuffs_base__error__disabled_by_previous_error
-               : wuffs_base__error__check_wuffs_version_missing;
+               : wuffs_base__error__initialize_not_called;
   }
   if ((self->private_impl.active_coroutine != 0) &&
       (self->private_impl.active_coroutine != 2)) {
@@ -9018,7 +9018,7 @@
   if (self->private_impl.magic != WUFFS_BASE__MAGIC) {
     return (self->private_impl.magic == WUFFS_BASE__DISABLED)
                ? wuffs_base__error__disabled_by_previous_error
-               : wuffs_base__error__check_wuffs_version_missing;
+               : wuffs_base__error__initialize_not_called;
   }
   if (!a_dst) {
     self->private_impl.magic = WUFFS_BASE__DISABLED;
@@ -10747,7 +10747,7 @@
   if ((initialize_flags & WUFFS_INITIALIZE__ALREADY_ZEROED) == 0) {
     memset(self, 0, sizeof_star_self);
   } else if (self->private_impl.magic != 0) {
-    return wuffs_base__error__check_wuffs_version_not_applicable;
+    return wuffs_base__error__initialize_falsely_claimed_already_zeroed;
   }
   {
     wuffs_base__status z = wuffs_crc32__ieee_hasher__initialize(
@@ -10826,7 +10826,7 @@
   if (self->private_impl.magic != WUFFS_BASE__MAGIC) {
     return (self->private_impl.magic == WUFFS_BASE__DISABLED)
                ? wuffs_base__error__disabled_by_previous_error
-               : wuffs_base__error__check_wuffs_version_missing;
+               : wuffs_base__error__initialize_not_called;
   }
   if ((self->private_impl.active_coroutine != 0) &&
       (self->private_impl.active_coroutine != 1)) {
@@ -11220,7 +11220,7 @@
   if ((initialize_flags & WUFFS_INITIALIZE__ALREADY_ZEROED) == 0) {
     memset(self, 0, sizeof_star_self);
   } else if (self->private_impl.magic != 0) {
-    return wuffs_base__error__check_wuffs_version_not_applicable;
+    return wuffs_base__error__initialize_falsely_claimed_already_zeroed;
   }
   {
     wuffs_base__status z = wuffs_adler32__hasher__initialize(
@@ -11299,7 +11299,7 @@
   if (self->private_impl.magic != WUFFS_BASE__MAGIC) {
     return (self->private_impl.magic == WUFFS_BASE__DISABLED)
                ? wuffs_base__error__disabled_by_previous_error
-               : wuffs_base__error__check_wuffs_version_missing;
+               : wuffs_base__error__initialize_not_called;
   }
   if ((self->private_impl.active_coroutine != 0) &&
       (self->private_impl.active_coroutine != 1)) {
diff --git a/test/c/std/gif.c b/test/c/std/gif.c
index 158a10c..b38cb46 100644
--- a/test/c/std/gif.c
+++ b/test/c/std/gif.c
@@ -106,15 +106,15 @@
   return NULL;
 }
 
-const char* test_basic_check_wuffs_version_not_called() {
+const char* test_basic_initialize_not_called() {
   CHECK_FOCUS(__func__);
   wuffs_gif__decoder dec = ((wuffs_gif__decoder){});
   wuffs_base__image_config ic = ((wuffs_base__image_config){});
   wuffs_base__io_reader src = ((wuffs_base__io_reader){});
   const char* status = wuffs_gif__decoder__decode_image_config(&dec, &ic, src);
-  if (status != wuffs_base__error__check_wuffs_version_missing) {
+  if (status != wuffs_base__error__initialize_not_called) {
     RETURN_FAIL("decode_image_config: got \"%s\", want \"%s\"", status,
-                wuffs_base__error__check_wuffs_version_missing);
+                wuffs_base__error__initialize_not_called);
   }
   return NULL;
 }
@@ -1589,14 +1589,14 @@
     // These basic tests are really testing the Wuffs compiler. They aren't
     // specific to the std/gif code, but putting them here is as good as any
     // other place.
-    test_basic_bad_receiver,                    //
-    test_basic_bad_sizeof_receiver,             //
-    test_basic_bad_wuffs_version,               //
-    test_basic_check_wuffs_version_not_called,  //
-    test_basic_status_is_error,                 //
-    test_basic_status_strings,                  //
-    test_basic_status_used_package,             //
-    test_basic_sub_struct_initializer,          //
+    test_basic_bad_receiver,            //
+    test_basic_bad_sizeof_receiver,     //
+    test_basic_bad_wuffs_version,       //
+    test_basic_initialize_not_called,   //
+    test_basic_status_is_error,         //
+    test_basic_status_strings,          //
+    test_basic_status_used_package,     //
+    test_basic_sub_struct_initializer,  //
 
     test_wuffs_gif_call_interleaved,                         //
     test_wuffs_gif_call_sequence,                            //