diff --git a/libc/test/src/stdio/sprintf_test.cpp b/libc/test/src/stdio/sprintf_test.cpp
--- a/libc/test/src/stdio/sprintf_test.cpp
+++ b/libc/test/src/stdio/sprintf_test.cpp
@@ -928,12 +928,16 @@
 
   // Length Modifier Tests.
 
-  // TODO: Fix long doubles (needs bigger table or alternate algorithm.)
-  // Currently the table values are generated, which is very slow.
+  // TODO(michaelrj): Add tests for LONG_DOUBLE_IS_DOUBLE and 128 bit long
+  // double systems.
+  // TODO(michaelrj): Fix the tests to only depend on the digits the long double
+  // is accurate for.
 
   written = __llvm_libc::sprintf(buff, "%Lf", 1.0L);
   ASSERT_STREQ_LEN(written, buff, "1.000000");
 
+#if defined(SPECIAL_X86_LONG_DOUBLE)
+
   written = __llvm_libc::sprintf(buff, "%Lf", 1e100L);
   ASSERT_STREQ_LEN(written, buff,
                    "99999999999999999996693535322073426194986990198284960792713"
@@ -941,8 +945,6 @@
 
   char big_buff[10000];
 
-  // written = __llvm_libc::sprintf(big_buff, "%Lf", 0x1p16383L);
-
   written = __llvm_libc::sprintf(big_buff, "%Lf", 1e1000L);
   ASSERT_STREQ_LEN(
       written, big_buff,
@@ -1035,10 +1037,8 @@
       "231934194956788626761834746430104077432547436359522462253411168467463134"
       "24896.000000");
 
-
   written = __llvm_libc::sprintf(big_buff, "%.10Lf", 1e-10L);
-  ASSERT_STREQ_LEN(
-      written, big_buff, "0.0000000001");
+  ASSERT_STREQ_LEN(written, big_buff, "0.0000000001");
 
   written = __llvm_libc::sprintf(big_buff, "%.7500Lf", 1e-4900L);
   ASSERT_STREQ_LEN(
@@ -1149,6 +1149,7 @@
       "570449525088342437216896462077260223998756027453411520977536701491759878"
       "422771447006016890777855573925295187921971811871399320142563330377888532"
       "179817332113");
+#endif // SPECIAL_X86_LONG_DOUBLE
 
   /*
     written = __llvm_libc::sprintf(buff, "%La", 0.1L);