diff --git a/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt b/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt
new file mode 100644
index 000000000..f8445615c
--- /dev/null
+++ b/ChangeLog.d/zeroizations_of_sensitive_data_in_PKCS5_and_SHA.txt
@@ -0,0 +1,5 @@
+Security
+   * Zeroising of local buffers and variables which are used for calculations
+     in mbedtls_pkcs5_pbkdf2_hmac() and mbedtls_internal_sha*_process()
+     functions to erase sensitive data from memory. Reported by
+     Johan Malmgren and Johan Uppman Bruce from Sectra.
diff --git a/library/pkcs5.c b/library/pkcs5.c
index 8a80aa5d0..69b85deeb 100644
--- a/library/pkcs5.c
+++ b/library/pkcs5.c
@@ -312,6 +312,10 @@ int mbedtls_pkcs5_pbkdf2_hmac( mbedtls_md_context_t *ctx, const unsigned char *p
                 break;
     }
 
+    /* Zeroise buffers to clear sensitive data from memory. */
+    mbedtls_platform_zeroize( work, MBEDTLS_MD_MAX_SIZE );
+    mbedtls_platform_zeroize( md1, MBEDTLS_MD_MAX_SIZE );
+
     return( 0 );
 }
 
diff --git a/library/sha1.c b/library/sha1.c
index 8682abd74..4bb51982f 100644
--- a/library/sha1.c
+++ b/library/sha1.c
@@ -313,6 +313,15 @@ int mbedtls_internal_sha1_process( mbedtls_sha1_context *ctx,
     ctx->state[3] += D;
     ctx->state[4] += E;
 
+    /* Zeroise buffers and variables to clear sensitive data from memory. */
+    mbedtls_platform_zeroize( &A, sizeof( A ) );
+    mbedtls_platform_zeroize( &B, sizeof( B ) );
+    mbedtls_platform_zeroize( &C, sizeof( C ) );
+    mbedtls_platform_zeroize( &D, sizeof( D ) );
+    mbedtls_platform_zeroize( &E, sizeof( E ) );
+    mbedtls_platform_zeroize( &W, sizeof( W ) );
+    mbedtls_platform_zeroize( &temp, sizeof( temp ) );
+
     return( 0 );
 }
 
diff --git a/library/sha256.c b/library/sha256.c
index 5169584b6..2decd08f0 100644
--- a/library/sha256.c
+++ b/library/sha256.c
@@ -281,6 +281,12 @@ int mbedtls_internal_sha256_process( mbedtls_sha256_context *ctx,
     for( i = 0; i < 8; i++ )
         ctx->state[i] += A[i];
 
+    /* Zeroise buffers and variables to clear sensitive data from memory. */
+    mbedtls_platform_zeroize( &A, sizeof( A ) );
+    mbedtls_platform_zeroize( &W, sizeof( W ) );
+    mbedtls_platform_zeroize( &temp1, sizeof( temp1 ) );
+    mbedtls_platform_zeroize( &temp2, sizeof( temp2 ) );
+
     return( 0 );
 }
 
diff --git a/library/sha512.c b/library/sha512.c
index 36d5d9614..37a01dd7b 100644
--- a/library/sha512.c
+++ b/library/sha512.c
@@ -312,6 +312,19 @@ int mbedtls_internal_sha512_process( mbedtls_sha512_context *ctx,
     ctx->state[6] += G;
     ctx->state[7] += H;
 
+    /* Zeroise buffers and variables to clear sensitive data from memory. */
+    mbedtls_platform_zeroize( &A, sizeof( A ) );
+    mbedtls_platform_zeroize( &B, sizeof( B ) );
+    mbedtls_platform_zeroize( &C, sizeof( C ) );
+    mbedtls_platform_zeroize( &D, sizeof( D ) );
+    mbedtls_platform_zeroize( &E, sizeof( E ) );
+    mbedtls_platform_zeroize( &F, sizeof( F ) );
+    mbedtls_platform_zeroize( &G, sizeof( G ) );
+    mbedtls_platform_zeroize( &H, sizeof( H ) );
+    mbedtls_platform_zeroize( &W, sizeof( W ) );
+    mbedtls_platform_zeroize( &temp1, sizeof( temp1 ) );
+    mbedtls_platform_zeroize( &temp2, sizeof( temp2 ) );
+
     return( 0 );
 }