diff --git a/libc/src/math/generic/scalbn.cpp b/libc/src/math/generic/scalbn.cpp
--- a/libc/src/math/generic/scalbn.cpp
+++ b/libc/src/math/generic/scalbn.cpp
@@ -14,11 +14,11 @@
 
 LLVM_LIBC_FUNCTION(double, scalbn, (double x, int n)) {
 #if !defined(__FLT_RADIX__)
-#error __FLT_RADIX__!=2.
-#elif __FLT_RADIX__ == 2
-  return fputil::ldexp(x, n);
-#else
 #error __FLT_RADIX__ undefined.
+#elif __FLT_RADIX__ != 2
+#error __FLT_RADIX__!=2, unimplemented.
+#else
+  return fputil::ldexp(x, n);
 #endif
 }
 
diff --git a/libc/src/math/generic/scalbnf.cpp b/libc/src/math/generic/scalbnf.cpp
--- a/libc/src/math/generic/scalbnf.cpp
+++ b/libc/src/math/generic/scalbnf.cpp
@@ -16,7 +16,7 @@
 #if !defined(__FLT_RADIX__)
 #error __FLT_RADIX__ undefined.
 #elif __FLT_RADIX__ != 2
-#error __FLT_RADIX__!=2.
+#error __FLT_RADIX__!=2, unimplemented.
 #else
   return fputil::ldexp(x, n);
 #endif
diff --git a/libc/src/math/generic/scalbnl.cpp b/libc/src/math/generic/scalbnl.cpp
--- a/libc/src/math/generic/scalbnl.cpp
+++ b/libc/src/math/generic/scalbnl.cpp
@@ -16,7 +16,7 @@
 #if !defined(__FLT_RADIX__)
 #error __FLT_RADIX__ undefined.
 #elif __FLT_RADIX__ != 2
-#error __FLT_RADIX__!=2.
+#error __FLT_RADIX__!=2, unimplemented.
 #else
   return fputil::ldexp(x, n);
 #endif