diff --git a/src/Makefile.am b/src/Makefile.am
index 38ab4647..08bd613a 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -526,7 +526,7 @@ check:
 		echo "TPM_LIBTPMS_CALLBACK occurrence has changed to $$n from $$exp"; \
 		exit 1; \
 	fi; \
-	n=`grep TPM_BUFFER_MAX tpm2/Implementation.h | grep -E "^#define" | wc -l`; \
+	n=`grep TPM2_GetBufferSize tpm2/Implementation.h | grep -E "^#define" | wc -l`; \
 	exp=2; \
 	if test $$n -ne $$exp; then \
 		echo "Lost patches to tpm2/Implementation.h ?"; \
diff --git a/src/tpm2/Implementation.h b/src/tpm2/Implementation.h
index f7e6a2e2..f1e4d163 100644
--- a/src/tpm2/Implementation.h
+++ b/src/tpm2/Implementation.h
@@ -376,8 +376,9 @@
 #define  CONTEXT_ENCRYPT_ALGORITHM      AES
 #define  NV_CLOCK_UPDATE_INTERVAL       12
 #define  NUM_POLICY_PCR                 1
-#define  MAX_COMMAND_SIZE               TPM_BUFFER_MAX
-#define  MAX_RESPONSE_SIZE              TPM_BUFFER_MAX
+#include "tpm_library_intern.h"
+#define  MAX_COMMAND_SIZE               TPM2_GetBufferSize()
+#define  MAX_RESPONSE_SIZE              TPM2_GetBufferSize()
 #define  ORDERLY_BITS                   8
 #define  MAX_SYM_DATA                   128
 #define  MAX_RNG_ENTROPY_SIZE           64
diff --git a/src/tpm_library_intern.h b/src/tpm_library_intern.h
index 136357f6..796522e5 100644
--- a/src/tpm_library_intern.h
+++ b/src/tpm_library_intern.h
@@ -134,4 +134,6 @@ TPM_RESULT CopyCachedState(enum TPMLIB_StateType st,
 const char *TPMLIB_StateTypeToName(enum TPMLIB_StateType st);
 enum TPMLIB_StateType TPMLIB_NameToStateType(const char *name);
 
+uint32_t TPM2_GetBufferSize(void);
+
 #endif /* TPM_LIBRARY_INTERN_H */
diff --git a/src/tpm_tpm2_interface.c b/src/tpm_tpm2_interface.c
index fa4268a5..a53db0f0 100644
--- a/src/tpm_tpm2_interface.c
+++ b/src/tpm_tpm2_interface.c
@@ -315,16 +315,36 @@ error:
     return NULL;
 }
 
+static uint32_t tpm2_buffersize = TPM_BUFFER_MAX;
+
 uint32_t TPM2_SetBufferSize(uint32_t wanted_size,
                             uint32_t *min_size,
                             uint32_t *max_size)
 {
-    /* FIXME: this needs to become adjustable */
+    const uint32_t min = MAX_CONTEXT_SIZE + 128;
+    const uint32_t max = TPM_BUFFER_MAX;
+
     if (min_size)
-        *min_size = MAX_COMMAND_SIZE;
+        *min_size = min;
     if (max_size)
-        *max_size = MAX_COMMAND_SIZE;
-    return MAX_COMMAND_SIZE;
+        *max_size = max;
+
+    if (wanted_size == 0)
+        return tpm2_buffersize;
+
+    if (wanted_size > max)
+        wanted_size = max;
+    else if (wanted_size < min)
+        wanted_size = min;
+
+    tpm2_buffersize = wanted_size;
+
+    return tpm2_buffersize;
+}
+
+uint32_t TPM2_GetBufferSize(void)
+{
+    return TPM2_SetBufferSize(0, NULL, NULL);
 }
 
 /*