diff --git a/envvar.c b/envvar.c
index 77518d2..e3769a8 100644
--- a/envvar.c
+++ b/envvar.c
@@ -93,6 +93,26 @@ typedef struct umem_env_item {
 static arg_process_t umem_backend_process;
 #endif
 
+#ifdef __GLIBC__
+/* replace getenv() with a specialized version that doesn't
+ * need to allocate memory.  We can't use strlen or strcmp
+ * here. */
+#include <unistd.h>
+static char *safe_getenv(const char *name)
+{
+	int i, l;
+	for (l = 0; name[l]; l++)
+		;
+	for (i = 0; __environ[i]; i++) {
+		if (!memcmp(__environ[i], name, l) && __environ[i][l] == '=') {
+			return &__environ[i][l+1];
+		}
+	}
+	return NULL;
+}
+#define getenv(x) safe_getenv(x)
+#endif
+
 static arg_process_t umem_log_process;
 
 const char *____umem_environ_msg_options = "-- UMEM_OPTIONS --";
@@ -553,6 +573,7 @@ umem_setup_envvars(int invalid)
 	static volatile enum {
 		STATE_START,
 		STATE_GETENV,
+		STATE_DLOPEN,
 		STATE_DLSYM,
 		STATE_FUNC,
 		STATE_DONE
@@ -577,6 +598,10 @@ umem_setup_envvars(int invalid)
 			where = "during getenv(3C) calls -- "
 			    "getenv(3C) results ignored.";
 			break;
+		case STATE_DLOPEN:
+			where = "during dlopen(3C) call -- "
+			    "_umem_*() results ignored.";
+			break;
 		case STATE_DLSYM:
 			where = "during dlsym(3C) call -- "
 			    "_umem_*() results ignored.";
@@ -623,6 +648,7 @@ umem_setup_envvars(int invalid)
 # define dlclose(a)		0
 # define dlerror()		0
 #endif
+	state = STATE_DLOPEN;
 	/* get a handle to the "a.out" object */
 	if ((h = dlopen(0, RTLD_FIRST | RTLD_LAZY)) != NULL) {
 		for (cur_env = umem_envvars; cur_env->env_name != NULL;
diff --git a/malloc.c b/malloc.c
index 45fae6e..7eec207 100644
--- a/malloc.c
+++ b/malloc.c
@@ -41,6 +41,10 @@
 
 #include "misc.h"
 
+#ifdef __GLIBC__
+# include <malloc.h>
+#endif
+
 /*
  * malloc_data_t is an 8-byte structure which is located "before" the pointer
  * returned from {m,c,re}alloc and memalign.  The first four bytes give
@@ -58,8 +62,12 @@ typedef struct malloc_data {
 	uint32_t malloc_stat; /* = UMEM_MALLOC_ENCODE(state, malloc_size) */
 } malloc_data_t;
 
+#ifdef __GLIBC__
+static void *umem_malloc_hook(size_t size_arg, const void *caller)
+#else
 void *
 malloc(size_t size_arg)
+#endif
 {
 #ifdef _LP64
 	uint32_t high_size = 0;
@@ -120,6 +128,7 @@ malloc(size_t size_arg)
 	return ((void *)ret);
 }
 
+#ifndef __GLIBC__
 void *
 calloc(size_t nelem, size_t elsize)
 {
@@ -138,6 +147,7 @@ calloc(size_t nelem, size_t elsize)
 	(void) memset(retval, 0, size);
 	return (retval);
 }
+#endif
 
 /*
  * memalign uses vmem_xalloc to do its work.
@@ -146,8 +156,12 @@ calloc(size_t nelem, size_t elsize)
  * code.
  */
 
+#ifdef __GLIBC__
+static void *umem_memalign_hook(size_t size_arg, size_t align, const void *caller)
+#else
 void *
 memalign(size_t align, size_t size_arg)
+#endif
 {
 	size_t size;
 	uintptr_t phase;
@@ -226,11 +240,13 @@ memalign(size_t align, size_t size_arg)
 	return ((void *)ret);
 }
 
+#ifndef __GLIBC__
 void *
 valloc(size_t size)
 {
 	return (memalign(pagesize, size));
 }
+#endif
 
 /*
  * process_free:
@@ -376,8 +392,12 @@ process_memalign:
 	return (1);
 }
 
+#ifdef __GLIBC__
+static void umem_free_hook(void *buf, const void *caller)
+#else
 void
 free(void *buf)
+#endif
 {
 	if (buf == NULL)
 		return;
@@ -388,8 +408,12 @@ free(void *buf)
 	(void) process_free(buf, 1, NULL);
 }
 
+#ifdef __GLIBC__
+static void *umem_realloc_hook(void *buf_arg, size_t newsize, const void *caller)
+#else
 void *
 realloc(void *buf_arg, size_t newsize)
+#endif
 {
 	size_t oldsize;
 	void *buf;
@@ -417,8 +441,25 @@ realloc(void *buf_arg, size_t newsize)
 	return (buf);
 }
 
+#ifdef __GLIBC__
+static void __attribute__((constructor)) umem_malloc_init_hook(void)
+{
+	if (__malloc_hook != umem_malloc_hook) {
+		umem_startup(NULL, 0, 0, NULL, NULL);
+		__malloc_hook = umem_malloc_hook;
+		__free_hook = umem_free_hook;
+		__realloc_hook = umem_realloc_hook;
+		__memalign_hook = umem_memalign_hook;
+	}
+}
+
+void (*__malloc_initialize_hook)(void) = umem_malloc_init_hook;
+
+#else
 void __attribute__((constructor))
 __malloc_umem_init (void)
 {
-  umem_startup(NULL, 0, 0, NULL, NULL);
+	umem_startup(NULL, 0, 0, NULL, NULL);
 }
+#endif
+