diff --git a/src/delta.c b/src/delta.c
index f76d8e2a..6ab6aa6b 100644
--- a/src/delta.c
+++ b/src/delta.c
@@ -83,7 +83,7 @@ static inline uint8_t *patch_read_cache(WB_PATCH_CTX *ctx)
 
         if (ctx->p_off < ctx->patch_cache_start +
                 (DELTA_PATCH_BLOCK_SIZE - BLOCK_HDR_SIZE))
-            return ctx->patch_cache + ctx->p_off;
+            return ctx->patch_cache + ctx->p_off - ctx->patch_cache_start;
     }
     ctx->patch_cache_start = ctx->p_off;
     ext_flash_check_read(
diff --git a/tools/test-delta.mk b/tools/test-delta.mk
index 66f3556a..006c2d59 100644
--- a/tools/test-delta.mk
+++ b/tools/test-delta.mk
@@ -6,11 +6,12 @@ test-delta-update:EXPVER=tools/test-expect-version/test-expect-version /dev/ttyA
 test-delta-update-ext:SIGN_ARGS?=--ecc256
 test-delta-update-ext:SIGN_DELTA_ARGS?=--ecc256 --encrypt /tmp/enc_key.der
 test-delta-update-ext:USBTTY?=/dev/ttyACM0
-test-delta-update-ext:TIMEOUT?=30
+test-delta-update-ext:TIMEOUT?=50
 test-delta-update-ext:EXPVER=tools/test-expect-version/test-expect-version /dev/ttyACM0
 
 test-delta-update: factory.bin test-app/image.bin tools/uart-flash-server/ufserver tools/delta/bmdiff tools/test-expect-version/test-expect-version
 	@st-flash reset
+	@sleep 2
 	@st-flash erase || st-flash erase
 	@diff .config config/examples/stm32wb-delta.config || (echo "\n\n*** Error: please copy config/examples/stm32wb-delta.config to .config to run this test\n\n" && exit 1)
 	$(SIGN_TOOL) $(SIGN_ARGS) --delta test-app/image_v1_signed.bin test-app/image.bin \
@@ -19,28 +20,32 @@ test-delta-update: factory.bin test-app/image.bin tools/uart-flash-server/ufserv
 		$(PRIVATE_KEY) 2
 	@st-flash write factory.bin 0x08000000
 	@echo Expecting version '1'
-	@(test `$(EXPVER)` -eq 1)
+	@(test `$(EXPVER)` -eq 1) || (st-flash reset && test `$(EXPVER)` -eq 1)
 	@echo
 	@sleep 2
 	@st-flash write test-app/image_v7_signed_diff.bin 0x0802C000
 	@sleep 2
 	@st-flash reset
 	@echo Expecting version '7'
-	@(test `$(EXPVER)` -eq 7)
+	@(test `$(EXPVER)` -eq 7) || (st-flash reset && test `$(EXPVER)` -eq 7)
 	@sleep 2
 	@st-flash reset
 	@echo Expecting version '1'
 	@(test `$(EXPVER)` -eq 1)
+	@sleep 2
+	@st-flash reset
+	@sleep 2
 	@st-flash erase || st-flash erase
 	@st-flash write factory.bin 0x08000000
 	@echo Expecting version '1'
-	@(test `$(EXPVER)` -eq 1)
-	@sleep 1
+	@test `$(EXPVER)` -eq 1
+	@sleep 2
 	@st-flash reset
+	@sleep 2
 	@st-flash write test-app/image_v2_signed_diff.bin 0x0802C000
 	@st-flash reset
 	@echo Expecting version '2'
-	@(test `$(EXPVER)` -eq 2)
+	@(test `$(EXPVER)` -eq 2) || (st-flash reset && test `$(EXPVER)` -eq 2)
 	@sleep 2
 	@st-flash reset
 	@echo Expecting version '2'
@@ -65,7 +70,9 @@ test-delta-update-ext: factory.bin test-app/image.bin tools/uart-flash-server/uf
 	@sleep $(TIMEOUT)
 	@killall ufserver
 	@st-flash reset
-	@sleep 3
+	@sleep 10
+	@st-flash reset
+	@sleep 5
 	@st-flash read boot_full.bin 0x0800C000 0x8000
 	@SIZE=`wc -c test-app/image_v7_signed.bin | cut -d" " -f 1`;  \
 		dd if=boot_full.bin of=boot.bin bs=1 count=$$SIZE
@@ -78,6 +85,9 @@ test-delta-update-ext: factory.bin test-app/image.bin tools/uart-flash-server/uf
 	@st-flash reset
 	@(tools/uart-flash-server/ufserver test-app/image_v7_signed_diff.bin $(USBTTY))&
 	@echo TEST INVERSE
+	@st-flash reset
+	@sleep 1
+	@st-flash reset
 	@sleep $(TIMEOUT)
 	@st-flash reset
 	@killall ufserver
diff --git a/tools/uart-flash-server/Makefile b/tools/uart-flash-server/Makefile
index 0fccf7d4..e744aab0 100644
--- a/tools/uart-flash-server/Makefile
+++ b/tools/uart-flash-server/Makefile
@@ -1,10 +1,21 @@
 CC=$(CROSS_COMPILE)gcc
 CFLAGS=-Wall -DWOLFSSL_DEBUG -DTFM_TIMING_RESISTANT -DWOLFBOOT_SIGN_ECC256 -DWOLFBOOT_HASH_SHA256 -g -ggdb -I../../include -I../../hal -Wextra
+Q?=@
+ifeq ($(V),1)
+   Q=
+endif
 
 EXE=ufserver
 
-$(EXE): $(EXE).o ../../src/libwolfboot.o
-	$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
+$(EXE): $(EXE).o libwolfboot.o
+	$(Q)$(CC) -o $@ $^ $(CFLAGS) $(LIBS)
+
+%.o: %.c
+	$(Q)$(CC) $(CFLAGS) -c -o $(@) $(^)
+
+libwolfboot.o: ../../src/libwolfboot.c
+	$(Q)$(CC) $(CFLAGS) -c -o $(@) $(^)
+
 
 clean:
-	rm -f *.o $(EXE) ../../src/libwolfboot.o
+	$(Q)rm -f *.o $(EXE)