diff --git a/library/md4.c b/library/md4.c
index 37056d966..97cb5f0aa 100644
--- a/library/md4.c
+++ b/library/md4.c
@@ -199,7 +199,7 @@ void md4_update( md4_context *ctx, const unsigned char *input, size_t ilen )
     size_t fill;
     uint32_t left;
 
-    if( ilen <= 0 )
+    if( ilen == 0 )
         return;
 
     left = ctx->total[0] & 0x3F;
diff --git a/library/md5.c b/library/md5.c
index 88d50c6c9..87e2b1d69 100644
--- a/library/md5.c
+++ b/library/md5.c
@@ -218,7 +218,7 @@ void md5_update( md5_context *ctx, const unsigned char *input, size_t ilen )
     size_t fill;
     uint32_t left;
 
-    if( ilen <= 0 )
+    if( ilen == 0 )
         return;
 
     left = ctx->total[0] & 0x3F;
diff --git a/library/ripemd160.c b/library/ripemd160.c
index 73da510e2..4781a7ddb 100644
--- a/library/ripemd160.c
+++ b/library/ripemd160.c
@@ -280,7 +280,7 @@ void ripemd160_update( ripemd160_context *ctx,
     size_t fill;
     uint32_t left;
 
-    if( ilen <= 0 )
+    if( ilen == 0 )
         return;
 
     left = ctx->total[0] & 0x3F;
diff --git a/library/sha1.c b/library/sha1.c
index 4b2d0636d..da69a8f6e 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -252,7 +252,7 @@ void sha1_update( sha1_context *ctx, const unsigned char *input, size_t ilen )
     size_t fill;
     uint32_t left;
 
-    if( ilen <= 0 )
+    if( ilen == 0 )
         return;
 
     left = ctx->total[0] & 0x3F;
diff --git a/library/sha256.c b/library/sha256.c
index 9e70ff90c..09165cc6f 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -249,7 +249,7 @@ void sha256_update( sha256_context *ctx, const unsigned char *input,
     size_t fill;
     uint32_t left;
 
-    if( ilen <= 0 )
+    if( ilen == 0 )
         return;
 
     left = ctx->total[0] & 0x3F;
diff --git a/library/sha512.c b/library/sha512.c
index 5537e8de9..c13e0d996 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -242,7 +242,7 @@ void sha512_update( sha512_context *ctx, const unsigned char *input,
     size_t fill;
     unsigned int left;
 
-    if( ilen <= 0 )
+    if( ilen == 0 )
         return;
 
     left = (unsigned int) (ctx->total[0] & 0x7F);