diff --git a/libc/malloc_debug/backtrace.cpp b/libc/malloc_debug/backtrace.cpp
index ab5c505..0649571 100644
--- a/libc/malloc_debug/backtrace.cpp
+++ b/libc/malloc_debug/backtrace.cpp
@@ -83,41 +83,24 @@
 
   uintptr_t ip = _Unwind_GetIP(context);
 
-  // The instruction pointer is pointing at the instruction after the return
-  // call on all architectures.
-  // Modify the pc to point at the real function.
-  if (ip != 0) {
-#if defined(__arm__)
-    // If the ip is suspiciously low, do nothing to avoid a segfault trying
-    // to access this memory.
-    if (ip >= 4096) {
-      // Check bits [15:11] of the first halfword assuming the instruction
-      // is 32 bits long. If the bits are any of these values, then our
-      // assumption was correct:
-      //  b11101
-      //  b11110
-      //  b11111
-      // Otherwise, this is a 16 bit instruction.
-      uint16_t value = (*reinterpret_cast<uint16_t*>(ip - 2)) >> 11;
-      if (value == 0x1f || value == 0x1e || value == 0x1d) {
-        ip -= 4;
-      } else {
-        ip -= 2;
-      }
-    }
-#elif defined(__aarch64__)
-    // All instructions are 4 bytes long, skip back one instruction.
-    ip -= 4;
+  // `ip` is the address of the instruction *after* the call site in
+  // `context`, so we want to back up by one instruction. This is hard for
+  // every architecture except arm64, so we just make sure we're *inside*
+  // that instruction, not necessarily at the start of it. (If the value
+  // is too low to be valid, we just leave it alone.)
+  if (ip >= 4096) {
+#if defined(__aarch64__)
+    ip -= 4;  // Exactly.
+#elif defined(__arm__) || defined(__riscv)
+    ip -= 2;  // At least.
 #elif defined(__i386__) || defined(__x86_64__)
-    // It's difficult to decode exactly where the previous instruction is,
-    // so subtract 1 to estimate where the instruction lives.
-    ip--;
+    ip -= 1;  // At least.
 #endif
+  }
 
-    // Do not record the frames that fall in our own shared library.
-    if (g_current_code_map && (ip >= g_current_code_map->start) && ip < g_current_code_map->end) {
-      return _URC_NO_REASON;
-    }
+  // Do not record the frames that fall in our own shared library.
+  if (g_current_code_map && (ip >= g_current_code_map->start) && ip < g_current_code_map->end) {
+    return _URC_NO_REASON;
   }
 
   state->frames[state->cur_frame++] = ip;