diff --git a/racket/src/racket/src/eval.c b/racket/src/racket/src/eval.c
index 59400b633c..b44f4e3712 100644
--- a/racket/src/racket/src/eval.c
+++ b/racket/src/racket/src/eval.c
@@ -172,6 +172,12 @@
 # define INIT_JIT_ON 0
 #endif
 
+#ifdef __GNUC__
+# ifdef MZ_PRECISE_GC
+#  pragma clang diagnostic ignored "-Wself-assign"
+# endif
+#endif
+
 /* globals */
 SHARED_OK int scheme_startup_use_jit = INIT_JIT_ON;
 void scheme_set_startup_use_jit(int v) { scheme_startup_use_jit =  v; }
diff --git a/racket/src/racket/src/file.c b/racket/src/racket/src/file.c
index aa2916a8c5..e2abaaf0ba 100644
--- a/racket/src/racket/src/file.c
+++ b/racket/src/racket/src/file.c
@@ -157,6 +157,12 @@ static int check_dos_slashslash_qm(const char *next, int len, int *drive_end,
 
 #define is_drive_letter(c) (((unsigned char)c < 128) && isalpha((unsigned char)c))
 
+#ifdef __GNUC__
+# ifdef MZ_PRECISE_GC
+#  pragma clang diagnostic ignored "-Wtautological-compare"
+# endif
+#endif
+
 /* local */
 static Scheme_Object *path_p(int argc, Scheme_Object **argv);
 static Scheme_Object *general_path_p(int argc, Scheme_Object **argv);
@@ -6311,13 +6317,16 @@ find_system_path(int argc, Scheme_Object **argv)
 
     ends_in_slash = (SCHEME_PATH_VAL(home))[SCHEME_PATH_LEN(home) - 1] == '/';
     
+    /* cast here avoids a clang warning: */
+# define mz_STR_OFFSET(s, d) ((const char *)s + d)
+
     if (which == id_init_file)
-      return append_path(home, scheme_make_path("/.racketrc" + ends_in_slash));
+      return append_path(home, scheme_make_path(mz_STR_OFFSET("/.racketrc", ends_in_slash)));
     if (which == id_pref_file) {
 #if defined(OS_X) && !defined(XONX)
-      return append_path(home, scheme_make_path("/org.racket-lang.prefs.rktd" + ends_in_slash));
+      return append_path(home, scheme_make_path(mz_STR_OFFSET("/org.racket-lang.prefs.rktd", ends_in_slash)));
 #else      
-      return append_path(home, scheme_make_path("/racket-prefs.rktd" + ends_in_slash));
+      return append_path(home, scheme_make_path(mz_STR_OFFSET("/racket-prefs.rktd", ends_in_slash)));
 #endif
     }
   }
diff --git a/racket/src/racket/src/jit.h b/racket/src/racket/src/jit.h
index 0dd237eadb..303c2ce608 100644
--- a/racket/src/racket/src/jit.h
+++ b/racket/src/racket/src/jit.h
@@ -31,6 +31,11 @@
 
 #ifdef __GNUC__
 #pragma GCC diagnostic ignored "-Waddress"
+# ifdef MZ_PRECISE_GC
+#  pragma clang diagnostic ignored "-Wtautological-compare"
+#  pragma clang diagnostic ignored "-Wself-assign"
+#  pragma clang diagnostic ignored "-Wconstant-logical-operand"
+# endif
 #endif
 
 /* Separate JIT_PRECISE_GC lets us test some 3m support in non-3m mode: */
diff --git a/racket/src/racket/src/read.c b/racket/src/racket/src/read.c
index b47715130a..d127e97269 100644
--- a/racket/src/racket/src/read.c
+++ b/racket/src/racket/src/read.c
@@ -47,6 +47,12 @@
 # include <malloc.h>
 #endif
 
+#ifdef __GNUC__
+# ifdef MZ_PRECISE_GC
+#  pragma clang diagnostic ignored "-Wself-assign"
+# endif
+#endif
+
 #define MAX_QUICK_SYMBOL_SIZE 64
 
 /* Init options for embedding: */