diff --git a/libavcodec/dsputil.c b/libavcodec/dsputil.c
index 4afe743b7197cb6453833769f80160ebcfbd118e..c4b627b6831c1f8c04e4a2005fdeb45a147f3f01 100644
--- a/libavcodec/dsputil.c
+++ b/libavcodec/dsputil.c
@@ -31,8 +31,8 @@
 #include "simple_idct.h"
 #include "faandct.h"
 
-uint8_t cropTbl[256 + 2 * MAX_NEG_CROP];
-uint32_t squareTbl[512];
+uint8_t cropTbl[256 + 2 * MAX_NEG_CROP] = {0, };
+uint32_t squareTbl[512] = {0, };
 
 const uint8_t ff_zigzag_direct[64] = {
     0,   1,  8, 16,  9,  2,  3, 10,
@@ -59,7 +59,7 @@ const uint8_t ff_zigzag248_direct[64] = {
 };
 
 /* not permutated inverse zigzag_direct + 1 for MMX quantizer */
-uint16_t __align8 inv_zigzag_direct16[64];
+uint16_t __align8 inv_zigzag_direct16[64] = {0, };
 
 const uint8_t ff_alternate_horizontal_scan[64] = {
     0,  1,   2,  3,  8,  9, 16, 17, 
diff --git a/libavcodec/utils.c b/libavcodec/utils.c
index 2f50c4d07d8c57af80e61c051656490f68184170..5e43d4452dc4f2aef1e862971f4f6cbe717032eb 100644
--- a/libavcodec/utils.c
+++ b/libavcodec/utils.c
@@ -112,7 +112,7 @@ void av_freep(void *arg)
 }
 
 /* encoder management */
-AVCodec *first_avcodec;
+AVCodec *first_avcodec = NULL;
 
 void register_avcodec(AVCodec *format)
 {
diff --git a/libavformat/utils.c b/libavformat/utils.c
index 94169adf92e790bc67725cb4e6b367aac98aceb7..b31f4c236adf08962cfca0f502f99db39640a250 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -21,9 +21,9 @@
 #undef NDEBUG
 #include <assert.h>
 
-AVInputFormat *first_iformat;
-AVOutputFormat *first_oformat;
-AVImageFormat *first_image_format;
+AVInputFormat *first_iformat = NULL;
+AVOutputFormat *first_oformat = NULL;
+AVImageFormat *first_image_format = NULL;
 
 void av_register_input_format(AVInputFormat *format)
 {