diff --git a/include/fmt/core.h b/include/fmt/core.h
index 6de0e386..6dc93540 100644
--- a/include/fmt/core.h
+++ b/include/fmt/core.h
@@ -34,13 +34,13 @@
 
 #ifdef __ICL
 #  define FMT_ICC_VERSION __ICL
-#  define FMT_ICC_POSIX 0
+#  define FMT_ICC_INTRINSIC_BUG 1
 #elif defined(__INTEL_COMPILER)
 #  define FMT_ICC_VERSION __INTEL_COMPILER
-#  define FMT_ICC_POSIX 1
+#  define FMT_ICC_INTRINSIC_BUG 0
 #else
 #  define FMT_ICC_VERSION 0
-#  define FMT_ICC_POSIX 1
+#  define FMT_ICC_INTRINSIC_BUG 0
 #endif
 
 #ifdef __NVCC__
diff --git a/include/fmt/format.h b/include/fmt/format.h
index c4acf2eb..677c6355 100644
--- a/include/fmt/format.h
+++ b/include/fmt/format.h
@@ -166,12 +166,12 @@ FMT_END_NAMESPACE
 #  define FMT_BUILTIN_CLZLL(n) __builtin_clzll(n)
 #endif
 #if (FMT_GCC_VERSION || FMT_HAS_BUILTIN(__builtin_ctz) || FMT_ICC_VERSION) && \
-    FMT_ICC_POSIX
+    !FMT_ICC_INTRINSIC_BUG
 #  define FMT_BUILTIN_CTZ(n) __builtin_ctz(n)
 #endif
 #if (FMT_GCC_VERSION || FMT_HAS_BUILTIN(__builtin_ctzll) || \
      FMT_ICC_VERSION) &&                                    \
-    FMT_ICC_POSIX
+    !FMT_ICC_INTRINSIC_BUG
 #  define FMT_BUILTIN_CTZLL(n) __builtin_ctzll(n)
 #endif