diff --git a/src/shims/unix/sync.rs b/src/shims/unix/sync.rs
index 6666ffbd1d..1a91219e01 100644
--- a/src/shims/unix/sync.rs
+++ b/src/shims/unix/sync.rs
@@ -277,6 +277,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_mutexattr_init` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let default_kind = this.eval_libc_i32("PTHREAD_MUTEX_DEFAULT");
         mutexattr_set_kind(this, attr_op, default_kind)?;
 
@@ -359,6 +366,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_mutex_init` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let attr = this.read_pointer(attr_op)?;
         let kind = if this.ptr_is_null(attr)? {
             this.eval_libc_i32("PTHREAD_MUTEX_DEFAULT")
@@ -513,6 +527,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_rwlock_rdlock` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let id = rwlock_get_id(this, rwlock_op)?;
         let active_thread = this.get_active_thread();
 
@@ -531,6 +552,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_rwlock_tryrdlock` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let id = rwlock_get_id(this, rwlock_op)?;
         let active_thread = this.get_active_thread();
 
@@ -548,6 +576,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_rwlock_wrlock` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let id = rwlock_get_id(this, rwlock_op)?;
         let active_thread = this.get_active_thread();
 
@@ -578,6 +613,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_rwlock_trywrlock` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let id = rwlock_get_id(this, rwlock_op)?;
         let active_thread = this.get_active_thread();
 
@@ -595,6 +637,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_rwlock_unlock` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let id = rwlock_get_id(this, rwlock_op)?;
         let active_thread = this.get_active_thread();
 
@@ -614,6 +663,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_rwlock_destroy` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let id = rwlock_get_id(this, rwlock_op)?;
 
         if this.rwlock_is_locked(id) {
@@ -638,6 +694,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_condattr_init` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         // The default value of the clock attribute shall refer to the system
         // clock.
         // https://pubs.opengroup.org/onlinepubs/9699919799/functions/pthread_condattr_setclock.html
@@ -704,6 +767,13 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
     ) -> InterpResult<'tcx, i32> {
         let this = self.eval_context_mut();
 
+        if !matches!(&*this.tcx.sess.target.os, "linux" | "macos") {
+            throw_unsup_format!(
+                "`pthread_cond_init` is not supported on {}",
+                this.tcx.sess.target.os
+            );
+        }
+
         let attr = this.read_pointer(attr_op)?;
         let clock_id = if this.ptr_is_null(attr)? {
             this.eval_libc_i32("CLOCK_REALTIME")