diff --git a/.gitignore b/.gitignore
index 50b09750..c82b9fb1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -83,3 +83,4 @@ config.log
 regress/map_crash
 regress/sigill
 regress/sigill2
+regress/block_test
diff --git a/include/uc_priv.h b/include/uc_priv.h
index 1494cc65..2703627c 100644
--- a/include/uc_priv.h
+++ b/include/uc_priv.h
@@ -163,6 +163,8 @@ struct uc_struct {
     uint64_t addr_end;  // address where emulation stops (@end param of uc_emu_start())
 
     int thumb;  // thumb mode for ARM
+    // full TCG cache leads to middle-block break in the last translation?
+    bool block_full;
 };
 
 #include "qemu_macro.h"
diff --git a/include/unicorn/unicorn.h b/include/unicorn/unicorn.h
index 161e7613..a3293920 100644
--- a/include/unicorn/unicorn.h
+++ b/include/unicorn/unicorn.h
@@ -121,7 +121,7 @@ typedef enum uc_err {
 
 // Callback function for tracing code (UC_HOOK_CODE & UC_HOOK_BLOCK)
 // @address: address where the code is being executed
-// @size: size of machine instruction being executed
+// @size: size of machine instruction(s) being executed, or 0 when size is unknown
 // @user_data: user data passed to tracing APIs.
 typedef void (*uc_cb_hookcode_t)(uch handle, uint64_t address, uint32_t size, void *user_data);
 
diff --git a/qemu/target-i386/translate.c b/qemu/target-i386/translate.c
index 15b941c4..7ce37ef8 100644
--- a/qemu/target-i386/translate.c
+++ b/qemu/target-i386/translate.c
@@ -8256,6 +8256,7 @@ static inline void gen_intermediate_code_internal(uint8_t *gen_opc_cc_op,
     target_ulong cs_base;
     int num_insns;
     int max_insns;
+    bool block_full = false;
 
     /* generate intermediate code */
     pc_start = tb->pc;
@@ -8349,7 +8350,9 @@ static inline void gen_intermediate_code_internal(uint8_t *gen_opc_cc_op,
         max_insns = CF_COUNT_MASK;
 
     // Unicorn: trace this block on request
-    if (env->uc->hook_block) {
+    // Only hook this block if it is not broken from previous translation due to
+    // full translation cache
+    if (env->uc->hook_block && !env->uc->block_full) {
         struct hook_struct *trace = hook_find((uch)env->uc, UC_HOOK_BLOCK, pc_start);
         if (trace) {
             env->uc->block_addr = pc_start;
@@ -8407,6 +8410,7 @@ static inline void gen_intermediate_code_internal(uint8_t *gen_opc_cc_op,
             num_insns >= max_insns) {
             gen_jmp_im(dc, pc_ptr - dc->cs_base);
             gen_eob(dc);
+            block_full = true;
             break;
         }
     }
@@ -8427,6 +8431,8 @@ done_generating:
         tb->size = pc_ptr - pc_start;
         // tb->icount = num_insns;
     }
+
+    env->uc->block_full = block_full;
 }
 
 void gen_intermediate_code(CPUX86State *env, TranslationBlock *tb)
diff --git a/qemu/translate-all.c b/qemu/translate-all.c
index 9723f23f..aaebee42 100644
--- a/qemu/translate-all.c
+++ b/qemu/translate-all.c
@@ -179,8 +179,10 @@ static int cpu_gen_code(CPUArchState *env, TranslationBlock *tb, int *gen_code_s
     gen_intermediate_code(env, tb);
 
     // Unicorn: when tracing block, patch 1st operand for block size
-    if (env->uc->hook_block) {
-        if (env->uc->block_addr == tb->pc)
+    if (env->uc->hook_block && env->uc->block_addr == tb->pc) {
+        if (env->uc->block_full)    // block size is unknown
+            *(s->gen_opparam_buf + 1) = 0;
+        else
             *(s->gen_opparam_buf + 1) = tb->size;
     }
 
diff --git a/regress/block_test.c b/regress/block_test.c
index ce5180c9..9d74d199 100755
--- a/regress/block_test.c
+++ b/regress/block_test.c
@@ -6,7 +6,7 @@
 
 #include <unicorn/unicorn.h>
 
-static count = 1;
+static int count = 1;
 
 // Callback function for tracing code (UC_HOOK_CODE & UC_HOOK_BLOCK)
 // @address: address where the code is being executed
@@ -79,4 +79,6 @@ int main() {
    fprintf(stderr, "ok %d - uc_emu_start\n", count++);
 
    fprintf(stderr, "ok %d - Done", count++);
+
+   return 0;
 }
diff --git a/uc.c b/uc.c
index 2011c693..65179095 100644
--- a/uc.c
+++ b/uc.c
@@ -414,6 +414,7 @@ uc_err uc_emu_start(uch handle, uint64_t begin, uint64_t until, uint64_t timeout
     uc->emu_counter = 0;
     uc->stop_request = false;
     uc->invalid_error = UC_ERR_OK;
+    uc->block_full = false;
 
     switch(uc->arch) {
         default: