diff --git a/libguile/jit.c b/libguile/jit.c
index f8b4e7546..76526f524 100644
--- a/libguile/jit.c
+++ b/libguile/jit.c
@@ -32,6 +32,7 @@
 #include "gsubr.h"
 #include "instructions.h"
 #include "intrinsics.h"
+#include "simpos.h" /* scm_getenv_int */
 #include "threads.h"
 #include "vm-builtins.h"
 #include "vm-operations.h"
@@ -121,6 +122,10 @@
 
 
 
+/* Threshold for when to JIT-compile a function.  Set from the
+   GUILE_JIT_THRESHOLD environment variable.  */
+uint32_t scm_jit_counter_threshold = -1;
+
 /* Entry trampoline: saves registers, initializes THREAD and SP
    registers, and jumps into mcode. */
 static void (*enter_mcode) (scm_thread *thread, const uint8_t *mcode);
@@ -4465,5 +4470,6 @@ scm_jit_state_free (scm_jit_state *j)
 void
 scm_init_jit (void)
 {
+  scm_jit_counter_threshold = scm_getenv_int ("GUILE_JIT_COUNTER_THRESHOLD", -1);
   scm_c_define_gsubr ("%jit-compile", 1, 0, 0, (scm_t_subr) scm_sys_jit_compile);
 }
diff --git a/libguile/jit.h b/libguile/jit.h
index ae5c9da21..a1863c2c0 100644
--- a/libguile/jit.h
+++ b/libguile/jit.h
@@ -48,10 +48,11 @@ enum scm_jit_counter_value
 {
   SCM_JIT_COUNTER_ENTRY_INCREMENT = 15,
   SCM_JIT_COUNTER_LOOP_INCREMENT = 1,
-  SCM_JIT_COUNTER_THRESHOLD = 50
 };
 #endif
 
+SCM_INTERNAL uint32_t scm_jit_counter_threshold;
+
 SCM_INTERNAL const uint8_t *scm_jit_compute_mcode (scm_thread *thread,
                                                    struct scm_jit_function_data *data);
 SCM_INTERNAL void scm_jit_enter_mcode (scm_thread *thread,
diff --git a/libguile/vm-engine.c b/libguile/vm-engine.c
index 58ff53cda..4356159ac 100644
--- a/libguile/vm-engine.c
+++ b/libguile/vm-engine.c
@@ -471,7 +471,7 @@ VM_NAME (scm_thread *thread)
           NEXT (0);
         }
 
-      if (data->counter > SCM_JIT_COUNTER_THRESHOLD)
+      if (data->counter > scm_jit_counter_threshold)
         {
           const uint8_t *mcode;
 
@@ -722,7 +722,7 @@ VM_NAME (scm_thread *thread)
 
       data = (struct scm_jit_function_data *) (ip + data_offset);
 
-      if (data->counter > SCM_JIT_COUNTER_THRESHOLD)
+      if (data->counter > scm_jit_counter_threshold)
         {
           const uint8_t *mcode;