diff --git a/README.md b/README.md
index f194eecdb..47ed1f9e1 100644
--- a/README.md
+++ b/README.md
@@ -21,8 +21,6 @@ This repository contains a version of Valgrind including a few patches to improv
 Note that every version from macOS 10.12 onwards currently has the following issues:
 
 - using threads and signals together is undefined (crashes, hanging, etc), note: a few tests were disabled because of that
-- drd crashes on 10.15 (probably onwards)
-- dhat crashes (seen macOS 14 arm64)
 
 ## Usage
 
diff --git a/coregrind/m_mach/dyld_cache.c b/coregrind/m_mach/dyld_cache.c
index 5d8158473..db76d6770 100644
--- a/coregrind/m_mach/dyld_cache.c
+++ b/coregrind/m_mach/dyld_cache.c
@@ -62,11 +62,13 @@ static void output_debug_info(const dyld_cache_header* dyld_cache);
 typedef struct {
   const dyld_cache_header* header;
   Addr slide;
+  Bool tried;
 } DYLDCache;
 
 static DYLDCache dyld_cache = {
   .header = NULL,
   .slide = 0,
+  .tried = False,
 };
 
 static Addr calculate_relative(const dyld_cache_header * header, Addr offset) {
@@ -208,13 +210,23 @@ Addr VG_(dyld_cache_get_slide)(void) {
   return dyld_cache.slide;
 }
 
-void VG_(dyld_cache_init)(void) {
+int ensure_init(void) {
+  if (dyld_cache.header != NULL) {
+    return 1;
+  }
+
+  // FIXME: unlikely race condition?
+  if (dyld_cache.tried) {
+    return 0;
+  }
+  dyld_cache.tried = True;
+
   if (!try_to_init()) {
     VG_(dmsg)(
       "WARNING: could not read from dyld shared cache (DSC)\n"
       "Some reports (especially memory leaks) might be missing or incorrect (false-positives)\n"
     );
-    return;
+    return 0;
   }
 #if defined(VGP_arm64_darwin)
   // We currently detect if dyld is loading/using a library by checking if stat64 fails.
@@ -225,11 +237,22 @@ void VG_(dyld_cache_init)(void) {
   VG_(dyld_cache_load_library)("/usr/lib/system/libsystem_pthread.dylib");
   VG_(dyld_cache_load_library)("/usr/lib/system/libsystem_platform.dylib");
 #endif
+
+  return 1;
+}
+
+void VG_(dyld_cache_init)(const HChar* tool) {
+  // drd crashes if you map memory segments in m_main
+  if (VG_(strcmp)(tool, "drd") == 0) {
+    return;
+  }
+
+  ensure_init();
 }
 
 int VG_(dyld_cache_might_be_in)(const HChar* path) {
   // If not init'd, there is no point
-  if (dyld_cache.header == NULL) {
+  if (!ensure_init()) {
     return 0;
   }
 
@@ -269,7 +292,7 @@ int VG_(dyld_cache_load_library)(const HChar* path) {
   SizeT len = 0;
 
   // If not init'd, there is no point trying
-  if (dyld_cache.header == NULL) {
+  if (!ensure_init()) {
     return 0;
   }
 
diff --git a/coregrind/m_main.c b/coregrind/m_main.c
index 432e264e4..099119db7 100644
--- a/coregrind/m_main.c
+++ b/coregrind/m_main.c
@@ -1949,9 +1949,10 @@ Int valgrind_main ( Int argc, HChar **argv, HChar **envp )
    // Initialize the dyld cache, which is required with macOS 11 (Big Sur) and onwards
    // as some system libraries aren't provided on the disk anymore
    //   p: none
+   // Note: some tools don't like to start mapping memory right way, so we do it lazily in those cases.
    //--------------------------------------------------------------
 #  if defined(VGO_darwin) && DARWIN_VERS >= DARWIN_11_00
-   VG_(dyld_cache_init)();
+   VG_(dyld_cache_init)(VG_(clo_toolname));
 #  endif
 
    //--------------------------------------------------------------
diff --git a/coregrind/pub_core_mach.h b/coregrind/pub_core_mach.h
index 19cfff90a..08193a4a6 100644
--- a/coregrind/pub_core_mach.h
+++ b/coregrind/pub_core_mach.h
@@ -72,7 +72,7 @@ extern void VG_(mach_record_system_memory)(void);
 #if DARWIN_VERS >= DARWIN_11_00
 // Dyld shared cache (DSC) parsing, which is required as system libraries are not provided on disk
 // starting with macOS 11.0 (Big Sur)
-extern void VG_(dyld_cache_init)(void);
+extern void VG_(dyld_cache_init)(const HChar*);
 extern int VG_(dyld_cache_might_be_in)(const HChar*);
 extern int VG_(dyld_cache_load_library)(const HChar*);
 extern Addr VG_(dyld_cache_get_slide)(void);
diff --git a/dhat/dh_main.c b/dhat/dh_main.c
index 9e6ec1c06..4098323d6 100644
--- a/dhat/dh_main.c
+++ b/dhat/dh_main.c
@@ -916,6 +916,10 @@ void dh_handle_noninsn_read_asciiz(CorePart part, ThreadId tid, const HChar* s,
    tl_assert(clo_mode == Heap);
 
    tl_assert(part == Vg_CoreSysCall);
+
+   if (str == 0)
+      return;
+
    dh_handle_noninsn_read(part, tid, s, str, VG_(strlen)((const HChar*)str+1));
 }