diff --git a/NEWS b/NEWS
index a6e58aa677a..dc8831bc882 100644
--- a/NEWS
+++ b/NEWS
@@ -10,6 +10,8 @@ PHP                                                                        NEWS
     referenced return). (Nikita)
   . Fixed bug #69676 (Resolution of self::FOO in class constants not correct).
     (Nikita)
+  . Fixed bug #74265 (Build problems after 7.0.17 release: undefined reference
+    to `isfinite'). (Nikita)
 
 - Date:
   . Fixed bug #72096 (Swatch time value incorrect for dates before 1970). (mcq8)
diff --git a/Zend/configure.in b/Zend/configure.in
index ec339eaef5d..6d4d450ea89 100644
--- a/Zend/configure.in
+++ b/Zend/configure.in
@@ -70,7 +70,7 @@ int zend_sprintf(char *buffer, const char *format, ...);
 #endif
 
 #ifndef zend_isnan
-#ifdef HAVE_DECL_ISNAN
+#if HAVE_DECL_ISNAN
 #define zend_isnan(a) isnan(a)
 #elif defined(HAVE_FPCLASS)
 #define zend_isnan(a) ((fpclass(a) == FP_SNAN) || (fpclass(a) == FP_QNAN))
@@ -79,7 +79,7 @@ int zend_sprintf(char *buffer, const char *format, ...);
 #endif
 #endif
 
-#ifdef HAVE_DECL_ISINF
+#if HAVE_DECL_ISINF
 #define zend_isinf(a) isinf(a)
 #elif defined(INFINITY)
 /* Might not work, but is required by ISO C99 */
@@ -90,7 +90,7 @@ int zend_sprintf(char *buffer, const char *format, ...);
 #define zend_isinf(a) 0
 #endif
 
-#if defined(HAVE_DECL_ISFINITE)
+#if HAVE_DECL_ISFINITE
 #define zend_finite(a) isfinite(a)
 #elif defined(HAVE_FINITE)
 #define zend_finite(a) finite(a)
diff --git a/configure.in b/configure.in
index c169e95fd8e..42fd0447090 100644
--- a/configure.in
+++ b/configure.in
@@ -75,7 +75,7 @@ int zend_sprintf(char *buffer, const char *format, ...);
 #endif
 
 #ifndef zend_isnan
-#ifdef HAVE_DECL_ISNAN
+#if HAVE_DECL_ISNAN
 #define zend_isnan(a) isnan(a)
 #elif defined(HAVE_FPCLASS)
 #define zend_isnan(a) ((fpclass(a) == FP_SNAN) || (fpclass(a) == FP_QNAN))
@@ -84,7 +84,7 @@ int zend_sprintf(char *buffer, const char *format, ...);
 #endif
 #endif
 
-#ifdef HAVE_DECL_ISINF
+#if HAVE_DECL_ISINF
 #define zend_isinf(a) isinf(a)
 #elif defined(INFINITY)
 /* Might not work, but is required by ISO C99 */
@@ -95,7 +95,7 @@ int zend_sprintf(char *buffer, const char *format, ...);
 #define zend_isinf(a) 0
 #endif
 
-#if defined(HAVE_DECL_ISFINITE)
+#if HAVE_DECL_ISFINITE
 #define zend_finite(a) isfinite(a)
 #elif defined(HAVE_FINITE)
 #define zend_finite(a) finite(a)
diff --git a/ext/standard/config.m4 b/ext/standard/config.m4
index d2afcf000d5..61eefdc339f 100644
--- a/ext/standard/config.m4
+++ b/ext/standard/config.m4
@@ -360,7 +360,7 @@ AC_TRY_RUN([
 #include <math.h>
 #include <stdlib.h>
 
-#ifdef HAVE_DECL_ISNAN
+#if HAVE_DECL_ISNAN
 #define zend_isnan(a) isnan(a)
 #elif defined(HAVE_FPCLASS)
 #define zend_isnan(a) ((fpclass(a) == FP_SNAN) || (fpclass(a) == FP_QNAN))
@@ -391,7 +391,7 @@ AC_TRY_RUN([
 #include <math.h>
 #include <stdlib.h>
 
-#ifdef HAVE_DECL_ISINF
+#if HAVE_DECL_ISINF
 #define zend_isinf(a) isinf(a)
 #elif defined(INFINITY)
 /* Might not work, but is required by ISO C99 */
@@ -425,7 +425,7 @@ AC_TRY_RUN([
 #include <math.h>
 #include <stdlib.h>
 
-#ifdef HAVE_DECL_ISINF
+#if HAVE_DECL_ISINF
 #define zend_isinf(a) isinf(a)
 #elif defined(INFINITY)
 /* Might not work, but is required by ISO C99 */
@@ -460,7 +460,7 @@ AC_TRY_RUN([
 #include <math.h>
 #include <stdlib.h>
 
-#ifdef HAVE_DECL_ISNAN
+#if HAVE_DECL_ISNAN
 #define zend_isnan(a) isnan(a)
 #elif defined(HAVE_FPCLASS)
 #define zend_isnan(a) ((fpclass(a) == FP_SNAN) || (fpclass(a) == FP_QNAN))