diff --git a/internal/c/parts/compression/compression.cpp b/internal/c/parts/compression/compression.cpp
index ecbfcaf37..bfb064ee7 100644
--- a/internal/c/parts/compression/compression.cpp
+++ b/internal/c/parts/compression/compression.cpp
@@ -8,13 +8,13 @@
 #include "miniz.h"
 
 uint32_t func__adler32(qbs *text) {
-    if (!text->len) return 0;
-    return (uint32) adler32(1, text->chr, text->len);
+    if (!text->len) return 1;
+    return (uint32_t) adler32(1, text->chr, text->len);
 }
 
 uint32_t func__crc32(qbs *text) {
     if (!text->len) return 0;
-    return (uint32) crc32(0, text->chr, text->len);
+    return (uint32_t) crc32(0, text->chr, text->len);
 }
 
 qbs *func__deflate(qbs *text) {
diff --git a/source/subs_functions/subs_functions.bas b/source/subs_functions/subs_functions.bas
index 1aaf810cf..e0bd102ef 100644
--- a/source/subs_functions/subs_functions.bas
+++ b/source/subs_functions/subs_functions.bas
@@ -3833,7 +3833,7 @@ id.subfunc = 1
 id.callname = "func__adler32"
 id.args = 1
 id.arg = MKL$(STRINGTYPE - ISPOINTER)
-id.ret = LONGTYPE - ISPOINTER
+id.ret = ULONGTYPE - ISPOINTER
 id.hr_syntax = "_ADLER32(dataString$)"
 regid
 
@@ -3844,7 +3844,7 @@ id.subfunc = 1
 id.callname = "func__crc32"
 id.args = 1
 id.arg = MKL$(STRINGTYPE - ISPOINTER)
-id.ret = LONGTYPE - ISPOINTER
+id.ret = ULONGTYPE - ISPOINTER
 id.hr_syntax = "_CRC32(dataString$)"
 regid