diff --git a/3.1/alpine3.19/Dockerfile b/3.1/alpine3.19/Dockerfile
index ab93cb5278..94b5ec47b4 100644
--- a/3.1/alpine3.19/Dockerfile
+++ b/3.1/alpine3.19/Dockerfile
@@ -84,9 +84,6 @@ RUN set -eux; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \
 	\
-# the configure script does not detect isnan/isinf as macros
-	export ac_cv_func_isnan=yes ac_cv_func_isinf=yes; \
-	\
 # hack in "ENABLE_PATH_CHECK" disabling to suppress:
 #   warning: Insecure world writable dir
 	{ \
diff --git a/3.1/alpine3.20/Dockerfile b/3.1/alpine3.20/Dockerfile
index 7b0a19ee4d..c23adc3660 100644
--- a/3.1/alpine3.20/Dockerfile
+++ b/3.1/alpine3.20/Dockerfile
@@ -84,9 +84,6 @@ RUN set -eux; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \
 	\
-# the configure script does not detect isnan/isinf as macros
-	export ac_cv_func_isnan=yes ac_cv_func_isinf=yes; \
-	\
 # hack in "ENABLE_PATH_CHECK" disabling to suppress:
 #   warning: Insecure world writable dir
 	{ \
diff --git a/3.2/alpine3.19/Dockerfile b/3.2/alpine3.19/Dockerfile
index 1c16ef224e..84e7747328 100644
--- a/3.2/alpine3.19/Dockerfile
+++ b/3.2/alpine3.19/Dockerfile
@@ -106,9 +106,6 @@ RUN set -eux; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \
 	\
-# the configure script does not detect isnan/isinf as macros
-	export ac_cv_func_isnan=yes ac_cv_func_isinf=yes; \
-	\
 # hack in "ENABLE_PATH_CHECK" disabling to suppress:
 #   warning: Insecure world writable dir
 	{ \
diff --git a/3.2/alpine3.20/Dockerfile b/3.2/alpine3.20/Dockerfile
index 2583cc82b8..e460aba190 100644
--- a/3.2/alpine3.20/Dockerfile
+++ b/3.2/alpine3.20/Dockerfile
@@ -106,9 +106,6 @@ RUN set -eux; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \
 	\
-# the configure script does not detect isnan/isinf as macros
-	export ac_cv_func_isnan=yes ac_cv_func_isinf=yes; \
-	\
 # hack in "ENABLE_PATH_CHECK" disabling to suppress:
 #   warning: Insecure world writable dir
 	{ \
diff --git a/3.3/alpine3.19/Dockerfile b/3.3/alpine3.19/Dockerfile
index 25844db3f6..41524f2a47 100644
--- a/3.3/alpine3.19/Dockerfile
+++ b/3.3/alpine3.19/Dockerfile
@@ -104,9 +104,6 @@ RUN set -eux; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \
 	\
-# the configure script does not detect isnan/isinf as macros
-	export ac_cv_func_isnan=yes ac_cv_func_isinf=yes; \
-	\
 # hack in "ENABLE_PATH_CHECK" disabling to suppress:
 #   warning: Insecure world writable dir
 	{ \
diff --git a/3.3/alpine3.20/Dockerfile b/3.3/alpine3.20/Dockerfile
index 549eb8f454..963c1110bf 100644
--- a/3.3/alpine3.20/Dockerfile
+++ b/3.3/alpine3.20/Dockerfile
@@ -104,9 +104,6 @@ RUN set -eux; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \
 	\
-# the configure script does not detect isnan/isinf as macros
-	export ac_cv_func_isnan=yes ac_cv_func_isinf=yes; \
-	\
 # hack in "ENABLE_PATH_CHECK" disabling to suppress:
 #   warning: Insecure world writable dir
 	{ \
diff --git a/3.4-rc/alpine3.19/Dockerfile b/3.4-rc/alpine3.19/Dockerfile
index b2082a609c..ff329f04c0 100644
--- a/3.4-rc/alpine3.19/Dockerfile
+++ b/3.4-rc/alpine3.19/Dockerfile
@@ -104,9 +104,6 @@ RUN set -eux; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \
 	\
-# the configure script does not detect isnan/isinf as macros
-	export ac_cv_func_isnan=yes ac_cv_func_isinf=yes; \
-	\
 # hack in "ENABLE_PATH_CHECK" disabling to suppress:
 #   warning: Insecure world writable dir
 	{ \
diff --git a/3.4-rc/alpine3.20/Dockerfile b/3.4-rc/alpine3.20/Dockerfile
index d69b2c4ad9..be4ce7f411 100644
--- a/3.4-rc/alpine3.20/Dockerfile
+++ b/3.4-rc/alpine3.20/Dockerfile
@@ -104,9 +104,6 @@ RUN set -eux; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \
 	\
-# the configure script does not detect isnan/isinf as macros
-	export ac_cv_func_isnan=yes ac_cv_func_isinf=yes; \
-	\
 # hack in "ENABLE_PATH_CHECK" disabling to suppress:
 #   warning: Insecure world writable dir
 	{ \
diff --git a/Dockerfile.template b/Dockerfile.template
index c5ceed1ca4..ceb8c320e5 100644
--- a/Dockerfile.template
+++ b/Dockerfile.template
@@ -215,9 +215,6 @@ RUN set -eux; \
 	patch -p1 -i thread-stack-fix.patch; \
 	rm thread-stack-fix.patch; \
 	\
-# the configure script does not detect isnan/isinf as macros
-	export ac_cv_func_isnan=yes ac_cv_func_isinf=yes; \
-	\
 {{ ) else "" end -}}
 # hack in "ENABLE_PATH_CHECK" disabling to suppress:
 #   warning: Insecure world writable dir