diff --git a/src/CHANGELOG b/src/CHANGELOG
index 715371c38..08695f227 100755
--- a/src/CHANGELOG
+++ b/src/CHANGELOG
@@ -95,6 +95,9 @@ and important fixes to let ECL work better with Slime.
 
  - ECL now implements EXT:*INVOKE-DEBUGGER-HOOK*, which works like *DEBUGGER-HOOK*
    but is also observed by BREAK. (SBCL extension adopted by ECL)
+ 
+ - The UFFI interface now supports C99 types, such as :int8-t, :uint32-t, etc,
+   but only when the corresponding types do exist in the underlying C environment.
 
 ;;; Local Variables: ***
 ;;; mode:text ***
diff --git a/src/aclocal.m4 b/src/aclocal.m4
index 7afea8939..568887fab 100644
--- a/src/aclocal.m4
+++ b/src/aclocal.m4
@@ -424,9 +424,11 @@ dnl have the right size;
 dnl
 AC_DEFUN(ECL_INTEGER_TYPES,[
 ECL_STDINT_HEADER=""
+ECL_UINT8_T=""
 ECL_UINT16_T=""
 ECL_UINT32_T=""
 ECL_UINT64_T=""
+ECL_INT8_T=""
 ECL_INT16_T=""
 ECL_INT32_T=""
 ECL_INT64_T=""
diff --git a/src/c/ffi.d b/src/c/ffi.d
index 29143b0f8..0e47fdc84 100644
--- a/src/c/ffi.d
+++ b/src/c/ffi.d
@@ -31,6 +31,10 @@ static const cl_object ecl_foreign_type_table[] = {
 	@':unsigned-int',
 	@':long',
 	@':unsigned-long',
+#ifdef ecl_uint8_t
+        @':int8-t',
+        @':uint8-t',
+#endif
 #ifdef ecl_uint16_t
         @':int16-t',
         @':uint16-t',
@@ -73,6 +77,10 @@ static unsigned int ecl_foreign_type_size[] = {
 	sizeof(unsigned int),
 	sizeof(long),
 	sizeof(unsigned long),
+#ifdef ecl_uint8_t
+        sizeof(ecl_int8_t),
+        sizeof(ecl_uint8_t),
+#endif
 #ifdef ecl_uint16_t
         sizeof(ecl_int16_t),
         sizeof(ecl_uint16_t),
@@ -126,13 +134,17 @@ static ffi_type *ecl_type_to_libffi_type[] = {
 	&ffi_type_uint, /*@':unsigned-int',*/
 	&ffi_type_slong, /*@':long',*/
 	&ffi_type_ulong, /*@':unsigned-long',*/
+#ifdef ecl_uint8_t
+        &ffi_type_sint8, /*@':int8-t',*/
+        &ffi_type_uint8, /*@':uint8-t',*/
+#endif
 #ifdef ecl_uint16_t
         &ffi_type_sint16, /*@':int16-t',*/
         &ffi_type_uint16, /*@':uint16-t',*/
 #endif
 #ifdef ecl_uint32_t
-        &ffi_type_sint32, /*@':int64-t',*/
-        &ffi_type_uint32, /*@':uint64-t',*/
+        &ffi_type_sint32, /*@':int32-t',*/
+        &ffi_type_uint32, /*@':uint32-t',*/
 #endif
 #ifdef ecl_uint64_t
         &ffi_type_sint64, /*@':int64-t',*/
diff --git a/src/configure b/src/configure
index deec25658..7f396262a 100755
--- a/src/configure
+++ b/src/configure
@@ -2360,7 +2360,7 @@ fi
 if test "${enable_precisegc+set}" = set; then
   enableval=$enable_precisegc; enable_precisegc=${enableval}
 else
-  enable_precisegc=no
+  enable_precisegc=yes
 fi
 
 
@@ -8700,9 +8700,11 @@ fi
 $as_echo "${CL_FIXNUM_TYPE}" >&6; }
 
 ECL_STDINT_HEADER=""
+ECL_UINT8_T=""
 ECL_UINT16_T=""
 ECL_UINT32_T=""
 ECL_UINT64_T=""
+ECL_INT8_T=""
 ECL_INT16_T=""
 ECL_INT32_T=""
 ECL_INT64_T=""
diff --git a/src/configure.in b/src/configure.in
index 956dbbb0b..c298a17dd 100644
--- a/src/configure.in
+++ b/src/configure.in
@@ -244,7 +244,7 @@ AC_ARG_ENABLE(precisegc,
   AS_HELP_STRING( [--enable-precisegc],
 		  [use type information during garbage collection. Requires Boehm-Weiser gc.]
 		  [(no|yes, default=NO)]),
-  [enable_precisegc=${enableval}], [enable_precisegc=no] )
+  [enable_precisegc=${enableval}], [enable_precisegc=yes] )
 
 dnl AC_ARG_ENABLE(debug,
 dnl   AS_HELP_STRING( [--enable-debug],
diff --git a/src/lsp/ffi.lsp b/src/lsp/ffi.lsp
index 5c5f1e58d..c1c1dae26 100644
--- a/src/lsp/ffi.lsp
+++ b/src/lsp/ffi.lsp
@@ -63,7 +63,11 @@
        (member name '(:byte :unsigned-byte :short :unsigned-short
 		      :int :unsigned-int :char :unsigned-char
 		      :long :unsigned-long :pointer-void :object
-		      :float :double :cstring)
+		      :float :double :cstring
+                      :int8-t #+uint16-t :int16-t
+                      #+uint32-t :int32-t #+uint64-t :int64-t
+                      :uint8-t #+uint16-t :uint16-t
+                      #+uint32-t :uint32-t #+uint64-t :uint64-t)
 	       :test 'eq)))
 
 (defmacro def-foreign-type (name definition)