diff --git a/flang/runtime/tools.h b/flang/runtime/tools.h
--- a/flang/runtime/tools.h
+++ b/flang/runtime/tools.h
@@ -134,7 +134,7 @@
       return FUNC<TypeCategory::Integer, 16>{}(std::forward<A>(x)...);
 #endif
     default:
-      terminator.Crash("unsupported INTEGER(KIND=%d)", kind);
+      terminator.Crash("not yet implemented: INTEGER(KIND=%d)", kind);
     }
   case TypeCategory::Real:
     switch (kind) {
@@ -156,7 +156,7 @@
       return FUNC<TypeCategory::Real, 16>{}(std::forward<A>(x)...);
 #endif
     default:
-      terminator.Crash("unsupported REAL(KIND=%d)", kind);
+      terminator.Crash("not yet implemented: REAL(KIND=%d)", kind);
     }
   case TypeCategory::Complex:
     switch (kind) {
@@ -178,7 +178,7 @@
       return FUNC<TypeCategory::Complex, 16>{}(std::forward<A>(x)...);
 #endif
     default:
-      terminator.Crash("unsupported COMPLEX(KIND=%d)", kind);
+      terminator.Crash("not yet implemented: COMPLEX(KIND=%d)", kind);
     }
   case TypeCategory::Character:
     switch (kind) {
@@ -189,7 +189,7 @@
     case 4:
       return FUNC<TypeCategory::Character, 4>{}(std::forward<A>(x)...);
     default:
-      terminator.Crash("unsupported CHARACTER(KIND=%d)", kind);
+      terminator.Crash("not yet implemented: CHARACTER(KIND=%d)", kind);
     }
   case TypeCategory::Logical:
     switch (kind) {
@@ -202,10 +202,11 @@
     case 8:
       return FUNC<TypeCategory::Logical, 8>{}(std::forward<A>(x)...);
     default:
-      terminator.Crash("unsupported LOGICAL(KIND=%d)", kind);
+      terminator.Crash("not yet implemented: LOGICAL(KIND=%d)", kind);
     }
   default:
-    terminator.Crash("unsupported type category(%d)", static_cast<int>(cat));
+    terminator.Crash(
+        "not yet implemented: type category(%d)", static_cast<int>(cat));
   }
 }
 
@@ -227,7 +228,7 @@
     return FUNC<16>{}(std::forward<A>(x)...);
 #endif
   default:
-    terminator.Crash("unsupported INTEGER(KIND=%d)", kind);
+    terminator.Crash("not yet implemented: INTEGER(KIND=%d)", kind);
   }
 }
 
@@ -253,7 +254,7 @@
     return FUNC<16>{}(std::forward<A>(x)...);
 #endif
   default:
-    terminator.Crash("unsupported REAL/COMPLEX(KIND=%d)", kind);
+    terminator.Crash("not yet implemented: REAL/COMPLEX(KIND=%d)", kind);
   }
 }
 
@@ -267,7 +268,7 @@
   case 4:
     return FUNC<4>{}(std::forward<A>(x)...);
   default:
-    terminator.Crash("unsupported CHARACTER(KIND=%d)", kind);
+    terminator.Crash("not yet implemented: CHARACTER(KIND=%d)", kind);
   }
 }
 
@@ -283,7 +284,7 @@
   case 8:
     return FUNC<8>{}(std::forward<A>(x)...);
   default:
-    terminator.Crash("unsupported LOGICAL(KIND=%d)", kind);
+    terminator.Crash("not yet implemented: LOGICAL(KIND=%d)", kind);
   }
 }