diff --git a/Makefile.dep b/Makefile.dep
index c2dcc9f659..cb6f3d2877 100644
--- a/Makefile.dep
+++ b/Makefile.dep
@@ -1050,7 +1050,7 @@ ifneq (,$(filter periph_uart_nonblocking,$(USEMODULE)))
 endif
 
 # include ztimer dependencies
-ifneq (,$(filter ztimer%,$(USEMODULE)))
+ifneq (,$(filter ztimer% %ztimer,$(USEMODULE)))
   include $(RIOTBASE)/sys/ztimer/Makefile.dep
 endif
 
diff --git a/sys/include/xtimer.h b/sys/include/xtimer.h
index a33e7cf82b..76b00e4233 100644
--- a/sys/include/xtimer.h
+++ b/sys/include/xtimer.h
@@ -590,14 +590,14 @@ static inline int xtimer_msg_receive_timeout64(msg_t *msg, uint64_t timeout);
  */
 #define XTIMER_HZ_BASE (1000000ul)
 
-#ifndef XTIMER_HZ
+#if !defined(XTIMER_HZ) && !defined(MODULE_XTIMER_ON_ZTIMER)
 /**
  * @brief  Frequency of the underlying hardware timer
  */
 #define XTIMER_HZ XTIMER_HZ_BASE
 #endif
 
-#ifndef XTIMER_SHIFT
+#if !defined(XTIMER_SHIFT) && !defined(MODULE_XTIMER_ON_ZTIMER)
 #if (XTIMER_HZ == 32768ul)
 /* No shift necessary, the conversion is not a power of two and is handled by
  * functions in tick_conversion.h */
@@ -634,7 +634,7 @@ static inline int xtimer_msg_receive_timeout64(msg_t *msg, uint64_t timeout);
 #else
 #error "XTIMER_SHIFT cannot be derived for given XTIMER_HZ, verify settings!"
 #endif
-#else
+#elif !defined(MODULE_XTIMER_ON_ZTIMER)
 #error "XTIMER_SHIFT is set relative to XTIMER_HZ, no manual define required!"
 #endif
 
diff --git a/sys/include/xtimer/tick_conversion.h b/sys/include/xtimer/tick_conversion.h
index a4306cf58f..23218390dd 100644
--- a/sys/include/xtimer/tick_conversion.h
+++ b/sys/include/xtimer/tick_conversion.h
@@ -77,7 +77,7 @@ static inline uint64_t _xtimer_usec_from_ticks64(uint64_t ticks) {
     return (ticks << XTIMER_SHIFT); /* multiply by power of two */
 }
 #endif /* defined(XTIMER_SHIFT) && (XTIMER_SHIFT != 0) */
-#elif XTIMER_HZ == (1000000ul)
+#elif (XTIMER_HZ == (1000000ul)) || defined(MODULE_XTIMER_ON_ZTIMER)
 /* This is the most straightforward as the xtimer API is based around
  * microseconds for representing time values. */
 static inline uint32_t _xtimer_usec_from_ticks(uint32_t ticks) {
diff --git a/sys/include/ztimer.h b/sys/include/ztimer.h
index c3f4d66fca..32c0a1fb2a 100644
--- a/sys/include/ztimer.h
+++ b/sys/include/ztimer.h
@@ -485,6 +485,7 @@ void ztimer_update_head_offset(ztimer_clock_t *clock);
  */
 void ztimer_init(void);
 
+#if defined(MODULE_ZTIMER_EXTEND) || defined(DOXYGEN)
 /**
  * @brief   Initialize possible ztimer extension intermediate timer
  *
@@ -501,6 +502,7 @@ static inline void ztimer_init_extend(ztimer_clock_t *clock)
         clock->ops->set(clock, clock->max_value >> 1);
     }
 }
+#endif /* MODULE_ZTIMER_EXTEND */
 
 /* default ztimer virtual devices */
 /**