diff --git a/libc/bionic/pthread_cond.cpp b/libc/bionic/pthread_cond.cpp
index 95a433c..4a69da5 100644
--- a/libc/bionic/pthread_cond.cpp
+++ b/libc/bionic/pthread_cond.cpp
@@ -120,9 +120,15 @@
 #endif
 };
 
+static_assert(sizeof(pthread_cond_t) == sizeof(pthread_cond_internal_t),
+              "pthread_cond_t should actually be pthread_cond_internal_t in implementation.");
+
+// For binary compatibility with old version of pthread_cond_t, we can't use more strict alignment
+// than 4-byte alignment.
+static_assert(alignof(pthread_cond_t) == 4,
+              "pthread_cond_t should fulfill the alignment requirement of pthread_cond_internal_t.");
+
 static pthread_cond_internal_t* __get_internal_cond(pthread_cond_t* cond_interface) {
-  static_assert(sizeof(pthread_cond_t) == sizeof(pthread_cond_internal_t),
-                "pthread_cond_t should actually be pthread_cond_internal_t in implementation.");
   return reinterpret_cast<pthread_cond_internal_t*>(cond_interface);
 }
 
diff --git a/libc/bionic/pthread_rwlock.cpp b/libc/bionic/pthread_rwlock.cpp
index f089940..8aa40ae 100644
--- a/libc/bionic/pthread_rwlock.cpp
+++ b/libc/bionic/pthread_rwlock.cpp
@@ -107,9 +107,15 @@
 #endif
 };
 
+static_assert(sizeof(pthread_rwlock_t) == sizeof(pthread_rwlock_internal_t),
+              "pthread_rwlock_t should actually be pthread_rwlock_internal_t in implementation.");
+
+// For binary compatibility with old version of pthread_rwlock_t, we can't use more strict
+// alignment than 4-byte alignment.
+static_assert(alignof(pthread_rwlock_t) == 4,
+             "pthread_rwlock_t should fulfill the alignment requirement of pthread_rwlock_internal_t.");
+
 static inline pthread_rwlock_internal_t* __get_internal_rwlock(pthread_rwlock_t* rwlock_interface) {
-  static_assert(sizeof(pthread_rwlock_t) == sizeof(pthread_rwlock_internal_t),
-                "pthread_rwlock_t should actually be pthread_rwlock_internal_t in implementation.");
   return reinterpret_cast<pthread_rwlock_internal_t*>(rwlock_interface);
 }
 
diff --git a/libc/include/pthread.h b/libc/include/pthread.h
index 09ea113..234a43d 100644
--- a/libc/include/pthread.h
+++ b/libc/include/pthread.h
@@ -78,7 +78,7 @@
 #else
   char __private[4];
 #endif
-} pthread_cond_t __attribute__((aligned(sizeof(long))));
+} pthread_cond_t __attribute__((aligned(4)));
 
 #define PTHREAD_COND_INITIALIZER  { { 0 } }
 
@@ -93,7 +93,7 @@
 #else
   char __private[40];
 #endif
-} pthread_rwlock_t __attribute__((aligned(8)));
+} pthread_rwlock_t __attribute__((aligned(4)));
 
 #define PTHREAD_RWLOCK_INITIALIZER  { { 0 } }