diff --git a/flang/runtime/character.cpp b/flang/runtime/character.cpp
--- a/flang/runtime/character.cpp
+++ b/flang/runtime/character.cpp
@@ -253,7 +253,7 @@
         result, string, terminator);
     break;
   default:
-    terminator.Crash("LEN_TRIM: bad KIND=%d", kind);
+    terminator.Crash("not yet implemented: LEN_TRIM: KIND=%d", kind);
   }
 }
 
@@ -454,7 +454,7 @@
         result, string, arg, back, terminator);
     break;
   default:
-    terminator.Crash("INDEX/SCAN/VERIFY: bad KIND=%d", kind);
+    terminator.Crash("not yet implemented: INDEX/SCAN/VERIFY: KIND=%d", kind);
   }
 }
 
diff --git a/flang/runtime/random.cpp b/flang/runtime/random.cpp
--- a/flang/runtime/random.cpp
+++ b/flang/runtime/random.cpp
@@ -108,7 +108,8 @@
     break;
 #endif
   default:
-    terminator.Crash("RANDOM_NUMBER(): bad REAL kind %d", kind);
+    terminator.Crash(
+        "not yet implemented: RANDOM_NUMBER(): REAL kind %d", kind);
   }
 }
 
@@ -127,7 +128,8 @@
     *size.OffsetElement<CppTypeFor<TypeCategory::Integer, 8>>() = 1;
     break;
   default:
-    terminator.Crash("RANDOM_SEED(SIZE=): bad kind %d\n", kind);
+    terminator.Crash(
+        "not yet implemented: RANDOM_SEED(SIZE=): kind %d\n", kind);
   }
 }
 
@@ -148,7 +150,7 @@
     seed = *put.OffsetElement<CppTypeFor<TypeCategory::Integer, 8>>();
     break;
   default:
-    terminator.Crash("RANDOM_SEED(PUT=): bad kind %d\n", kind);
+    terminator.Crash("not yet implemented: RANDOM_SEED(PUT=): kind %d\n", kind);
   }
   {
     CriticalSection critical{lock};
@@ -186,7 +188,7 @@
     *got.OffsetElement<CppTypeFor<TypeCategory::Integer, 8>>() = seed;
     break;
   default:
-    terminator.Crash("RANDOM_SEED(GET=): bad kind %d\n", kind);
+    terminator.Crash("not yet implemented: RANDOM_SEED(GET=): kind %d\n", kind);
   }
 }
 } // extern "C"
diff --git a/flang/runtime/tools.cpp b/flang/runtime/tools.cpp
--- a/flang/runtime/tools.cpp
+++ b/flang/runtime/tools.cpp
@@ -106,7 +106,8 @@
 
 void CheckIntegerKind(Terminator &terminator, int kind, const char *intrinsic) {
   if (kind < 1 || kind > 16 || (kind & (kind - 1)) != 0) {
-    terminator.Crash("%s: bad KIND=%d argument", intrinsic, kind);
+    terminator.Crash(
+        "not yet implemented: %s: KIND=%d argument", intrinsic, kind);
   }
 }
 } // namespace Fortran::runtime
diff --git a/flang/runtime/transformational.cpp b/flang/runtime/transformational.cpp
--- a/flang/runtime/transformational.cpp
+++ b/flang/runtime/transformational.cpp
@@ -106,7 +106,7 @@
           static_cast<char32_t>(' '));
       break;
     default:
-      terminator.Crash("EOSHIFT: bad CHARACTER kind %d", kind);
+      terminator.Crash("not yet implemented: EOSHIFT: CHARACTER kind %d", kind);
     }
   } else {
     std::memset(result.raw().base_addr, 0, bytes);