diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 727b2394a6..5877c54a26 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1431,6 +1431,8 @@ gcov:
     # Help gcovr process the nasty tricks in lib/dns/code.h, where we include C
     # source files from lib/dns/rdata/*/, using an even nastier trick.
     - find lib/dns/rdata/* -name "*.c" -execdir cp -f "{}" ../../ \;
+    # Help gcovr process inline function in the isc/hash.h
+    - cp -f lib/isc/include/isc/hash.h lib/dns/hash.h
     # Generate XML file in the Cobertura XML format suitable for use by GitLab
     # for the purpose of displaying code coverage information in the diff view
     # of a given merge request.
diff --git a/lib/isc/include/isc/hash.h b/lib/isc/include/isc/hash.h
index 80e50da83d..c3926157d0 100644
--- a/lib/isc/include/isc/hash.h
+++ b/lib/isc/include/isc/hash.h
@@ -19,6 +19,7 @@
 #include <isc/assertions.h>
 #include <isc/lang.h>
 #include <isc/types.h>
+#include <isc/util.h>
 
 #define ISC_HASHSIZE(bits)  (UINT64_C(1) << (bits))
 #define ISC_HASH_OVERCOMMIT 3
@@ -80,12 +81,12 @@ isc_hash64(const void *data, const size_t length, const bool case_sensitive);
  * \li a hash value of length 'bits'.
  */
 #define ISC_HASH_GOLDENRATIO_32 0x61C88647
-#define isc_hash_bits32(val, bits)                                      \
-	({                                                              \
-		REQUIRE(bits <= 32U);                                   \
-		uint32_t __v = (val & 0xffff);                          \
-		__v = ((__v * ISC_HASH_GOLDENRATIO_32) >> (32 - bits)); \
-		__v;                                                    \
-	})
+
+static inline uint32_t
+isc_hash_bits32(uint32_t val, unsigned int bits) {
+	ISC_REQUIRE(bits <= ISC_HASH_MAX_BITS);
+	/* High bits are more random. */
+	return (val * ISC_HASH_GOLDENRATIO_32 >> (32 - bits));
+}
 
 ISC_LANG_ENDDECLS